Samsung limits the number of tracks in a stream (video + audio + subtitles) to a total of 30.
The fix is to remove the unnecessary audio and subtitle tracks using MKVToolNix or similar tools.
Also note that Samsung TVs do not support DTS or TrueHD audio, so it will be transcoded by Plex Media Server to a supported format.
This can also cause problems with video transcoding. Depending on the version of Tizen, transcoded audio + subtitles may result in a video transcode.
Here’s some additional detail:
