I’m on WebOS with a similar problem: Plex for WebOS cannot play burned-in subtitles - #11 by efalsken
I can play the videos without subtitles and I can play them if I change Subtitle Burn-In to “Never”. But if I leave it on “always” or “Automatic” and play some PGS or ASS subtitles, then I get the Playback Error immediately when starting any video.
