I’m having a similar issue, but I’m using My Cloud Home WD.
Some files are working perfectly and some when connected to my Apple TV I get the same message “playback terminated…”…
I’ve tried to look for information but this post is the closest to my issue I found.
I tried on my iPad, Apple TV and web…but it’s always the same issue it’s always the same movie that don’t work…I checked if the files were corrupted or anything but I can read them with VLC from my computer easily…
I tried to analyse, refresh the data…nothing seems to work…I’m sure there’s something I’ve done wrong…but I’m lost…
I tried to uninstall Plex on my WD Home Cloud and reinstall again and I finally reuploaded all the movies everything was working but the subtitle fetch…all my movie were playing again…then I tried to fix the subtitles issues by reconfiguring open subtitles…it wasn’t working yesterday…but today the subtitles seem to work fine…but now when I play a movie I get the sa,e message again…
“Playback was terminated by the server. Conversion failed. The transcoder exited due to an error.”