Lately I've been watching quite a bit of shows offline. What I've noticed is that the episodes I watch offline, don't get a watched status in Trakt, even if the database status for the episode is updated to match the watched status.
I'm using the latest Emby for Android with Emby server running on a Synology NAS (while that shouldn't really matter). I have a download set so that Android app will always download 2 episodes to my mobile device and removes the watched episodes automatically. As mentioned, the Emby server is tracking the correct watched status, but Trakt isn't being updated.
This is a long running issue and hasn't been recently introduced, I just haven't had the time to report it. Also as a related note, the watched time seems to be a bit off, since the latest episode of the series watched offline doesn't show up in the "Up next" list. This might or might not be related.
Any other information I could give to debug this further?