It looks like some people's saved data got borked. We found the source of the problem. TLDR Beat Banger was using the name of the current mod pack and the current level to try and locate the saved data; this meant that if you changed the name of your mod pack or your level, then it could not properly access the save data in your app data folder.
Mod packs and acts now use an md5 hash As a permanent fingerprint that your mod pack can use to identify its location in your saved data. So, long story short, you won't lose any more of your saved data if you leave the act ID and the level ID untouched. ✨
Additions
Added Cathy Act / Level IDs
Added Zoe Act / Level IDs
Added Gale Act / Level IDs
Added Claire Act / Level IDs
Added Dawna Act / Level IDs
Fixes
Fixed modpack level index desync
Fixed cutscenes not unlocking after beating a level
Fixed crash when no difficulties are valid