The back up process can be a bit tricky - I’ve lost quite a few sounds migrating from an AK to an A4. Saving at the Project level didn’t quite catch everything the manual says it will catch (I was missing Banks, Sounds). I did my best to back up at every level (project, bank, sound, etc.) and that saved me quite a lot of pain.
The trouble seemed to be though that when backing up (for example) Sounds it was actually backing up something else, not sure if that was a bug or just user error… Make a few folders for multiple back up “techniques” - label it properly and you should be ok.
AdamJay has the right idea - Back up your back ups