WMP videos in BigBox have a corrupted effect at start

[salofan]

Having weird issues with videos in BigBox. Am on the current 13.22 beta, but was noticing this issue beforehand, as well. I'm using Windows Media Player for the video player per the current guidance. For a bit of context - my computer has a LG monitor and a Sony X77L television directly hooked up to it. I have a RTX 3070 for my graphics card. BigBox is set to open on the Sony TV. 

All videos played on my TV have a corrupted, black-screen effect for the first second or two. The sound plays, but the video image is glitching at the beginning. I've attached a short recording of what it looks like:

 

This effect happens on all MP4 videos: the Colorful platform sets, emumovies video clips, etc. 

Weirdly, this effect only happens on the TV - if I move BigBox over to my monitor, everything is normal, with no annoying black / artifacting effects.

And - webm files don't seem to have this issue and play fine. When I convert an MP4 to a webm, it plays fine on the TV through WMP.

Whenever I play videos independently on WMP legacy player on the TV, sans BigBox, the same black screen effect happens for a second or two. On the monitor - all fine.

Further, using VLC as the media player on the TV works just fine, regardless of the video format. Same with the modern media player that is included with Windows 11. The issues only seem to arise when playing MP4 videos - on my TV - using Windows Media Player legacy.

It looks like this is an issue with WMP, not BigBox, or it's an issue with some sort of weird interplay between WMP legacy and my Sony TV. Maybe something to do with my graphics card? I'm not sure why videos are working fine on one screen but not the other. Am I missing some codec that covers this scenario? I've installed the mega version of the K-lite codec pack. Nvidia drivers are up to date. Attempts to find solutions on the internet have not turned up anything.

Switching to VLC in BigBox for the video player solves this issue on my TV, but that introduces the stability problems warned about after a few minutes, and BB inevitably freezes up.

Has anyone else had this issue? Unfortunately, this is rendering BigBox pretty much unusable for me, as it's set up to be used on my television. I've been trying to track down the issue here for the better part of a week. Any help would be greatly appreciated.