Cards are sporadically reset to Learn/New

There are several inconsistencies there – rep count 0, due date missing, memory state missing, “Last Review” date, but is still New. All of that together looks just like a sync issue would look.

The question is – do you sync when you open the app AND when you close/leave the app, on every device, every time? If you’ve got cards with review history on AnkiDroid and edits on desktop at the same time, they can definitely end up in an inconsistent state like this. Add-ons that make changes “on sync”/“after sync” can aggravate the problem – and the FSRS Helper is not immune, if you use that functionality. Happily, that add-on can also be the cure.

See the what-to-do-now steps at the end of: Scheduling differences between Anki desktop and Android - #4 by Danika_Dakika