I have found a very strange issue when playing DVD MKV files with a DTS track on the ROKU Plex channel. What happens is this: The Mpeg2 video track is transcoded by Plex to h.264 as it should be, and the DTS is a direct play / stream. However the audio is extremely choppy almost like a pulsating choppy, it's not smooth playback at all.
I have a 2016 Premiere+, and a 2017 Ultra, and a 2016 Streaming Stick. The ultra, and Premiere+ have the issue with DTS unless I play a file that's natively h.264, and then audio is fine. Anything else that has to transcode causes the issue.
However, the 2016 Streaming stick with same Plex channel version, and a different software line, doesn't have the issue. I'm wanting to find out if I need to address this issue with Plex, or if this is a RoKU issue.