I’m running PMS under Docker on Synology, viewing on AppleTV, and tuning with an HDHomeRun.
I have Auto-Select Subtitle Mode set to “Always Enabled”. This works great for movie/tv files served by Plex, but not on streams from the tuner.
If I view Playback Settings by swiping down on the stream, I see “Unknown (Closed Captions)” under “subtitles”. It is checked by default, which is good! However no subtitles are shown.
If I switch it to “off” and back to “unknown” again, the subtitles appear.
I see the same behavior on web and AppleTV, so this seems like a server bug.