I am a novice at this but i can report
MKV currently does not play for me, maybe it is a DTS sound issue that is the problem as i converted an MKV container to MP4 making the sound AAC and it plays without issue, does anyone with knowledge in media formats have an idea if it is the sound causing my issue?

---------- Post added at 19:18 ---------- Previous post was at 17:41 ----------
Done some more testing, MKV play fine with either AC3 or AAC audio.