When playing files, Plex or XB1 is changing video output ratio and size

I’ve tested the same video files on other devices (ipads and roku players) and they play in the correct size on the screen. For some reason when I press play on my xbox 1 it resizes the video output to just about 50% of my tv screen, centered with black space all around it. When I exit out of playback, everything reverts back to normal size and I experience crackling in my xbox audio output. I’ve tried searching the forums, but I will admit I don’t know how to better describe the problem for a better search.