Hey, I just did some more experimenting and have some additional observations. The short answer is that this may be a problem with the Plex server, not Infuse.
I flagged the last 2 episodes of a show’s season as unwatched, then started the first of those 2. After a few seconds into playback, I chapter-forwarded to the end to force the next episode to start playing. After a few seconds, I exited out the the list of the episodes for the series. At this moment, the last episode was still flagged as unwatched. When I backed out a level, the season showed in my “Recently Added” list up top with the orange bar still indicating that there were unwatched episodes. Going back in and out had no effect on the “unwatched” status of the episode. When I forced a refresh from the icon up top, the episode at that point got flagged as watched (and thus, the whole season).
From that, it seems Infuse is getting the “watched” status from Plex, although if it’s sending something to Plex to make it think it was watched, I cannot say.
EDIT: ok, I don’t think it is the Plex server. I can’t replicate the problem on Plex’ own app on the ATV. But here’s what I did find. After forwarding through the first of those 2 same episodes to get to the second in Plex, and after aborting playback of the 2nd after it started, that last episode remained flagged as unwatched in Plex, and showed the same in Infuse. When I repeated the process in Infuse as before and got the “watched” flag applied incorrectly on that last episode, I went back to Plex and Plex still correctly shows that same episode as unwatched. If I check directly via Plex Server’s web browser interface, it also still correctly shows that episode as unwatched.