diff --git a/.vscode/launch.json b/.vscode/launch.json
index d16f1ca4f..74f72b826 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -23,6 +23,12 @@
       "name": "Haxe Eval",
       "type": "haxe-eval",
       "request": "launch"
+    },
+    {
+      // Attaches the debugger to an already running game
+      "name": "HXCPP - Attach",
+      "type": "hxcpp",
+      "request": "attach"
     }
   ]
 }
diff --git a/source/funkin/PauseSubState.hx b/source/funkin/PauseSubState.hx
index a074410ea..2ce9abf65 100644
--- a/source/funkin/PauseSubState.hx
+++ b/source/funkin/PauseSubState.hx
@@ -240,7 +240,7 @@ class PauseSubState extends MusicBeatSubState
 
           case 'Exit to Chart Editor':
             this.close();
-            if (FlxG.sound.music != null) FlxG.sound.music.stop();
+            if (FlxG.sound.music != null) FlxG.sound.music.pause(); // Don't reset song position!
             PlayState.instance.close(); // This only works because PlayState is a substate!
 
           case 'BACK':
diff --git a/source/funkin/data/DataParse.hx b/source/funkin/data/DataParse.hx
index 4a422b368..64a53d2a4 100644
--- a/source/funkin/data/DataParse.hx
+++ b/source/funkin/data/DataParse.hx
@@ -1,13 +1,15 @@
 package funkin.data;
 
 import funkin.data.song.importer.FNFLegacyData.LegacyNote;
-import hxjsonast.Json;
-import hxjsonast.Tools;
-import hxjsonast.Json.JObjectField;
-import haxe.ds.Either;
-import funkin.data.song.importer.FNFLegacyData.LegacyNoteSection;
 import funkin.data.song.importer.FNFLegacyData.LegacyNoteData;
+import funkin.data.song.importer.FNFLegacyData.LegacyNoteSection;
 import funkin.data.song.importer.FNFLegacyData.LegacyScrollSpeeds;
+import haxe.ds.Either;
+import hxjsonast.Json;
+import hxjsonast.Json.JObjectField;
+import hxjsonast.Tools;
+import thx.semver.Version;
+import thx.semver.VersionRule;
 
 /**
  * `json2object` has an annotation `@:jcustomparse` which allows for mutation of parsed values.
@@ -23,7 +25,8 @@ class DataParse
    * `@:jcustomparse(funkin.data.DataParse.stringNotEmpty)`
    * @param json Contains the `pos` and `value` of the property.
    * @param name The name of the property.
-   * @throws If the property is not a string or is empty.
+   * @throws Error If the property is not a string or is empty.
+   * @return The string value.
    */
   public static function stringNotEmpty(json:Json, name:String):String
   {
@@ -37,6 +40,42 @@ class DataParse
     }
   }
 
+  /**
+   * `@:jcustomparse(funkin.data.DataParse.semverVersion)`
+   * @param json Contains the `pos` and `value` of the property.
+   * @param name The name of the property.
+   * @return The value of the property as a `thx.semver.Version`.
+   */
+  public static function semverVersion(json:Json, name:String):Version
+  {
+    switch (json.value)
+    {
+      case JString(s):
+        if (s == "") throw 'Expected version property $name to be non-empty.';
+        return s;
+      default:
+        throw 'Expected version property $name to be a string, but it was ${json.value}.';
+    }
+  }
+
+  /**
+   * `@:jcustomparse(funkin.data.DataParse.semverVersionRule)`
+   * @param json Contains the `pos` and `value` of the property.
+   * @param name The name of the property.
+   * @return The value of the property as a `thx.semver.VersionRule`.
+   */
+  public static function semverVersionRule(json:Json, name:String):VersionRule
+  {
+    switch (json.value)
+    {
+      case JString(s):
+        if (s == "") throw 'Expected version rule property $name to be non-empty.';
+        return s;
+      default:
+        throw 'Expected version rule property $name to be a string, but it was ${json.value}.';
+    }
+  }
+
   /**
    * Parser which outputs a Dynamic value, either a object or something else.
    * @param json
diff --git a/source/funkin/data/DataWrite.hx b/source/funkin/data/DataWrite.hx
index 41993107f..2f3a7632f 100644
--- a/source/funkin/data/DataWrite.hx
+++ b/source/funkin/data/DataWrite.hx
@@ -1,6 +1,8 @@
 package funkin.data;
 
 import funkin.util.SerializerUtil;
+import thx.semver.Version;
+import thx.semver.VersionRule;
 
 /**
  * `json2object` has an annotation `@:jcustomwrite` which allows for custom serialization of values to be written to JSON.
@@ -9,9 +11,30 @@ import funkin.util.SerializerUtil;
  */
 class DataWrite
 {
+  /**
+   * `@:jcustomwrite(funkin.data.DataWrite.dynamicValue)`
+   * @param value
+   * @return String
+   */
   public static function dynamicValue(value:Dynamic):String
   {
     // Is this cheating? Yes. Do I care? No.
     return SerializerUtil.toJSON(value);
   }
+
+  /**
+   * `@:jcustomwrite(funkin.data.DataWrite.semverVersion)`
+   */
+  public static function semverVersion(value:Version):String
+  {
+    return value.toString();
+  }
+
+  /**
+   * `@:jcustomwrite(funkin.data.DataWrite.semverVersionRule)`
+   */
+  public static function semverVersionRule(value:VersionRule):String
+  {
+    return value.toString();
+  }
 }
diff --git a/source/funkin/data/song/SongData.hx b/source/funkin/data/song/SongData.hx
index 9340e46c9..88993e519 100644
--- a/source/funkin/data/song/SongData.hx
+++ b/source/funkin/data/song/SongData.hx
@@ -12,6 +12,8 @@ class SongMetadata
    *
    */
   // @:default(funkin.data.song.SongRegistry.SONG_METADATA_VERSION)
+  @:jcustomparse(funkin.data.DataParse.semverVersion)
+  @:jcustomwrite(funkin.data.DataWrite.semverVersion)
   public var version:Version;
 
   @:default("Unknown")
@@ -203,6 +205,8 @@ class SongMusicData
    *
    */
   // @:default(funkin.data.song.SongRegistry.SONG_METADATA_VERSION)
+  @:jcustomparse(funkin.data.DataParse.semverVersion)
+  @:jcustomwrite(funkin.data.DataWrite.semverVersion)
   public var version:Version;
 
   @:default("Unknown")
@@ -367,6 +371,8 @@ class SongCharacterData
 class SongChartData
 {
   @:default(funkin.data.song.SongRegistry.SONG_CHART_DATA_VERSION)
+  @:jcustomparse(funkin.data.DataParse.semverVersion)
+  @:jcustomwrite(funkin.data.DataWrite.semverVersion)
   public var version:Version;
 
   public var scrollSpeed:Map<String, Float>;
diff --git a/source/funkin/data/song/SongDataUtils.hx b/source/funkin/data/song/SongDataUtils.hx
index ee3dfe98c..3ff3943c6 100644
--- a/source/funkin/data/song/SongDataUtils.hx
+++ b/source/funkin/data/song/SongDataUtils.hx
@@ -246,7 +246,8 @@ class SongDataUtils
 
 typedef SongClipboardItems =
 {
-  ?valid:Bool,
-  notes:Array<SongNoteData>,
-  events:Array<SongEventData>
+  @:optional
+  var valid:Bool;
+  var notes:Array<SongNoteData>;
+  var events:Array<SongEventData>;
 }
diff --git a/source/funkin/data/song/migrator/SongData_v2_0_0.hx b/source/funkin/data/song/migrator/SongData_v2_0_0.hx
index 935e7349c..eeeed2f2b 100644
--- a/source/funkin/data/song/migrator/SongData_v2_0_0.hx
+++ b/source/funkin/data/song/migrator/SongData_v2_0_0.hx
@@ -24,6 +24,8 @@ class SongMetadata_v2_0_0
   // ==========
   // UNMODIFIED VALUES
   // ==========
+  @:jcustomparse(funkin.data.DataParse.semverVersion)
+  @:jcustomwrite(funkin.data.DataWrite.semverVersion)
   public var version:Version;
 
   @:default("Unknown")
diff --git a/source/funkin/play/HealthIcon.hx b/source/funkin/play/HealthIcon.hx
index 5b9c8ec75..958933df8 100644
--- a/source/funkin/play/HealthIcon.hx
+++ b/source/funkin/play/HealthIcon.hx
@@ -129,7 +129,6 @@ class HealthIcon extends FlxSprite
     if (value == characterId) return value;
 
     characterId = value ?? Constants.DEFAULT_HEALTH_ICON;
-    loadCharacter(characterId);
     return characterId;
   }
 
@@ -138,7 +137,6 @@ class HealthIcon extends FlxSprite
     if (value == isPixel) return value;
 
     isPixel = value;
-    loadCharacter(characterId);
     return isPixel;
   }
 
@@ -165,8 +163,11 @@ class HealthIcon extends FlxSprite
   {
     if (data == null)
     {
-      this.isPixel = false;
       this.characterId = Constants.DEFAULT_HEALTH_ICON;
+      this.isPixel = false;
+
+      loadCharacter(characterId);
+
       this.size.set(1.0, 1.0);
       this.offset.x = 0.0;
       this.offset.y = 0.0;
@@ -174,8 +175,11 @@ class HealthIcon extends FlxSprite
     }
     else
     {
-      this.isPixel = data.isPixel ?? false;
       this.characterId = data.id;
+      this.isPixel = data.isPixel ?? false;
+
+      loadCharacter(characterId);
+
       this.size.set(data.scale ?? 1.0, data.scale ?? 1.0);
       this.offset.x = (data.offsets != null) ? data.offsets[0] : 0.0;
       this.offset.y = (data.offsets != null) ? data.offsets[1] : 0.0;
diff --git a/source/funkin/play/PlayState.hx b/source/funkin/play/PlayState.hx
index 8b47e6ebd..9ccc66f69 100644
--- a/source/funkin/play/PlayState.hx
+++ b/source/funkin/play/PlayState.hx
@@ -698,7 +698,15 @@ class PlayState extends MusicBeatSubState
       FlxG.sound.music.pause();
       FlxG.sound.music.time = (startTimestamp);
 
-      vocals = currentChart.buildVocals();
+      if (!overrideMusic)
+      {
+        vocals = currentChart.buildVocals();
+
+        if (vocals.members.length == 0)
+        {
+          trace('WARNING: No vocals found for this song.');
+        }
+      }
       vocals.pause();
       vocals.time = 0;
 
diff --git a/source/funkin/play/song/Song.hx b/source/funkin/play/song/Song.hx
index f996d75ef..60b8b9864 100644
--- a/source/funkin/play/song/Song.hx
+++ b/source/funkin/play/song/Song.hx
@@ -154,6 +154,12 @@ class Song implements IPlayStateScriptedClass implements IRegistryEntry<SongMeta
     {
       if (metadata == null || metadata.playData == null) continue;
 
+      // If there are no difficulties in the metadata, there's a problem.
+      if (metadata.playData.difficulties.length == 0)
+      {
+        throw 'Song $id has no difficulties listed in metadata!';
+      }
+
       // There may be more difficulties in the chart file than in the metadata,
       // (i.e. non-playable charts like the one used for Pico on the speaker in Stress)
       // but all the difficulties in the metadata must be in the chart file.
diff --git a/source/funkin/save/Save.hx b/source/funkin/save/Save.hx
index 2666d2bff..54b66605c 100644
--- a/source/funkin/save/Save.hx
+++ b/source/funkin/save/Save.hx
@@ -421,6 +421,8 @@ typedef RawSaveData =
   /**
    * A semantic versioning string for the save data format.
    */
+  @:jcustomparse(funkin.data.DataParse.semverVersion)
+  @:jcustomwrite(funkin.data.DataWrite.semverVersion)
   var version:Version;
 
   var api:SaveApiData;
diff --git a/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx b/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx
index 91576f2ee..c26f6c805 100644
--- a/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorDialogHandler.hx
@@ -404,7 +404,6 @@ class ChartEditorDialogHandler
           {
             if (ChartEditorAudioHandler.loadInstFromBytes(state, selectedFile.bytes, instId))
             {
-              trace('Selected file: ' + selectedFile.fullPath);
               #if !mac
               NotificationManager.instance.addNotification(
                 {
@@ -415,13 +414,12 @@ class ChartEditorDialogHandler
                 });
               #end
 
+              state.switchToCurrentInstrumental();
               dialog.hideDialog(DialogButton.APPLY);
               removeDropHandler(onDropFile);
             }
             else
             {
-              trace('Failed to load instrumental (${selectedFile.fullPath})');
-
               #if !mac
               NotificationManager.instance.addNotification(
                 {
@@ -452,6 +450,7 @@ class ChartEditorDialogHandler
           });
         #end
 
+        state.switchToCurrentInstrumental();
         dialog.hideDialog(DialogButton.APPLY);
         removeDropHandler(onDropFile);
       }
@@ -570,6 +569,12 @@ class ChartEditorDialogHandler
 
     var newSongMetadata:SongMetadata = new SongMetadata('', '', 'default');
 
+    newSongMetadata.playData.difficulties = switch (targetVariation)
+    {
+      case 'erect': ['erect', 'nightmare'];
+      default: ['easy', 'normal', 'hard'];
+    };
+
     var inputSongName:Null<TextField> = dialog.findComponent('inputSongName', TextField);
     if (inputSongName == null) throw 'Could not locate inputSongName TextField in Song Metadata dialog';
     inputSongName.onChange = function(event:UIEvent) {
diff --git a/source/funkin/ui/debug/charting/ChartEditorState.hx b/source/funkin/ui/debug/charting/ChartEditorState.hx
index 30d8fde7e..40f841fd8 100644
--- a/source/funkin/ui/debug/charting/ChartEditorState.hx
+++ b/source/funkin/ui/debug/charting/ChartEditorState.hx
@@ -554,6 +554,9 @@ class ChartEditorState extends HaxeUIState
     notePreviewDirty = true;
     notePreviewViewportBoundsDirty = true;
 
+    // Make sure the difficulty we selected is in the list of difficulties.
+    currentSongMetadata.playData.difficulties.pushUnique(selectedDifficulty);
+
     return selectedDifficulty;
   }
 
@@ -971,6 +974,7 @@ class ChartEditorState extends HaxeUIState
       result = [];
       trace('Initializing blank note data for difficulty ' + selectedDifficulty);
       currentSongChartData.notes.set(selectedDifficulty, result);
+      currentSongMetadata.playData.difficulties.pushUnique(selectedDifficulty);
       return result;
     }
     return result;
@@ -979,6 +983,7 @@ class ChartEditorState extends HaxeUIState
   function set_currentSongChartNoteData(value:Array<SongNoteData>):Array<SongNoteData>
   {
     currentSongChartData.notes.set(selectedDifficulty, value);
+    currentSongMetadata.playData.difficulties.pushUnique(selectedDifficulty);
     return value;
   }
 
@@ -4089,7 +4094,7 @@ class ChartEditorState extends HaxeUIState
     }
 
     subStateClosed.add(fixCamera);
-    subStateClosed.add(updateConductor);
+    subStateClosed.add(resetConductorAfterTest);
 
     FlxTransitionableState.skipNextTransIn = false;
     FlxTransitionableState.skipNextTransOut = false;
@@ -4122,10 +4127,9 @@ class ChartEditorState extends HaxeUIState
     add(this.component);
   }
 
-  function updateConductor(_:FlxSubState = null):Void
+  function resetConductorAfterTest(_:FlxSubState = null):Void
   {
-    var targetPos = scrollPositionInMs;
-    Conductor.update(targetPos);
+    moveSongToScrollPosition();
   }
 
   public function postLoadInstrumental():Void
@@ -4179,12 +4183,14 @@ class ChartEditorState extends HaxeUIState
   function moveSongToScrollPosition():Void
   {
     // Update the songPosition in the audio tracks.
-    if (audioInstTrack != null) audioInstTrack.time = scrollPositionInMs + playheadPositionInMs;
+    if (audioInstTrack != null)
+    {
+      audioInstTrack.time = scrollPositionInMs + playheadPositionInMs;
+      // Update the songPosition in the Conductor.
+      Conductor.update(audioInstTrack.time);
+    }
     if (audioVocalTrackGroup != null) audioVocalTrackGroup.time = scrollPositionInMs + playheadPositionInMs;
 
-    // Update the songPosition in the Conductor.
-    Conductor.update(audioInstTrack.time);
-
     // We need to update the note sprites because we changed the scroll position.
     noteDisplayDirty = true;
   }
diff --git a/source/funkin/util/tools/ArrayTools.hx b/source/funkin/util/tools/ArrayTools.hx
index 67cc1c041..1c9f38de5 100644
--- a/source/funkin/util/tools/ArrayTools.hx
+++ b/source/funkin/util/tools/ArrayTools.hx
@@ -38,6 +38,19 @@ class ArrayTools
     return null;
   }
 
+  /**
+   * Push an element to the array if it is not already present.
+   * @param input The array to push to
+   * @param element The element to push
+   * @return Whether the element was pushed
+   */
+  public static function pushUnique<T>(input:Array<T>, element:T):Bool
+  {
+    if (input.contains(element)) return false;
+    input.push(element);
+    return true;
+  }
+
   /**
    * Remove all elements from the array, without creating a new array.
    * @param array The array to clear.