I am having a similar issue using the POV addon in Kodi. Upon completion of watching a show/movie, Trakt either ticks the show as ‘watched’ or I have to mark it ‘watched’. Later, I find the show is no longer ticked as ‘watched’.
I’ve signed out of my account, revoked access to Kodi/POV, signed back into my account, and reauthorized Kodi/POV and the issue is still not resolved. I appreciate your help in resolving this issue.