Black Video Playback on RPi 4

I just upgraded to the RPi4 from a RPi2B+ where I was previously using openelec to playback some mkv and avi files off of a samba share. The RPi4 is a clean install of the RPi4 version of libreelec (and I've attempted to re-image twice just in case) and doesn't have any kind of crazy settings or changes made to it. For whatever reason, video will NOT playback on the RPi4 where it used to play fine on the RPi2. Audio comes through nice and crisp, no hitches. Subtitles even show perfectly and time correctly, but the video is just blank. Doesn't matter the filetype, doesn't matter if it's in 480p, 720p or 1080p, I get zero playback visually. No errors displayed, the logs seem to indicate it thinks it's playing back fine, but no image is shown. The UI is working great and seems responsive enough. This is being done on a 4K tv, and I have tried to change the display resolution to 1080p60,1080p30 and even 720p60 but no matter what I do, all videos both local and over samba are displayed as completely black. I tried googling for some solutions but the only complaints I can see from anyone are over 4K playback, which I'm not even trying to do yet. As a final note, when I enable debugging/logging the display fps seems to be locked around 15fps for some reason (not sure if that's just a caveat of the debugging or not) and CPU usage never peaks above 40% or so and temps are under 45 degrees C. Any help or tips would be greatly appreciated.