I am using v66.0.1. TV shows are not syncing their watched status, even if the watch from Trakt do appear in the history.
When I go to the account settings on my phone (OnePlus Nord on Android 12), I see that the last sync of the account is two weeks ago. The auto-sync is enabled and if I do a sync now there, nothing happen (and the last sync date does not update).
I have disabled all battery optimisation on the app as well.
Welcome! Maybe you already did, but can you just try to disconnect and re-connect the Trakt account in SeriesGuide?
Yes indeed I tried that but without any success.
However, I just thought about something else. DAVx5 is showing me a notification since about the same time about suspended sync because of storage running low (despite several GB available). The issue is described there Storage low, Android wont run sync · Discussion #99 · bitfireAT/davx5-ose · GitHub
I did some cleanup and indeed, SeriesGuide started to sync again.
Maybe it would be worth showing the same kind of notification than DAVx5 in that case or doing the same kind of transition “transitioning from Android sync framework to the work manager lib”