Having a very odd scenario happen to be that seems specific only to my computer when i watch plex on it. I work from home and have 3 monitors, so I watch a lot of my plex server on my work computer. The mark as watched button has gone missing. I cant find it anywhere, not at the top on specific file, or season, or even when trying to specifically tag that file as watched on the dashboard via the 3 dot settings. Also the video files do not automatically update as watched when the video file has finished playing at the end.
Furthermore I use google chrome and clearing the cache/browser history/ etc and rebooting did not resolve the issue. I have firefox installed but rarely if ever use it, and have the same issue there. The weirdest part is when I remote into my server at home on the very same master account for plex i can mark any media as watched and it records my progress of all watched media as well as marking them automatically watched when I finish watching them. Its very odd and I have never seen anything like it. Here is a screenshot of me remoted into my server on the left and personal computer on the right for reference.
Screenshot: https://gyazo.com/f83d114af43a541155414fe09b69ba5d
