Weird Chromecast issue, story inside

Hey all weird issue Plex will not play a show have via Chromecast. Its a .mkv, which most of my media is. When I hit play it pushes to chromecast and I see the background image of the show then it buffers for a few secs. After that where it normally plays it goes to black screen and the timestamp doesn't move on TV. The timestamp however does move on my phone.

This media works on everything else (phone, comp, tablet) just not Chromecast. Its every episode of the show it seems like. All other shows work just fine.

I've updated and restarted Plex/Chromecast and nothing.

Just wanna watch me some naruto! Lol. Just curious if anyone has run into this issue