Also, this can be a result of Microsoft One Drive syncing and/or then Disk Cleanup settings deleting the local copy of your document folder(s) for "reasons".
This can happen more often if "Sync Your Settings" usage is enable on the PC, so that another Windows computer with your Use account on it/them will send or receive the contents of the User folder (of which is the parent folder containing Document and done to the game settings) which can result in "different" game settings getting mixed up.