Just reading up about WaterFox and this was a poster's issue with InFormEnter
"Rated 2 out of 5
by Firefox user 12946727,
a year agoI lost profile data many times so far. It is very disturbing. I think this is because this add-on saves data to Firefox Sync. Adding a new browser profile to Firefox Sync creates an empty InFormEntter+ profile on that new Firefox profile, which is copied to all profiles via Firefox Sync and loses all data."
So, I'm not alone, though the actual cause is still not certain.