I've noticed that if I start up the game with different mod-directory switches to point to different mod packs (but every other path and game setting are the same), that at least one mod that adds achievements, those achievements are reset.
Changed in Version: 0.17.65
- Modded achievements and their progress are now stored even when the mods adding extra achievements are temporarily removed. Up to 5000 modded achievements are stored indefinitely.
To do this I had to have a custom saving format for modded achievements, let me know if you notice any issues.