Video not playing in Quicktime when resolution is small

So I have a video that I need to be in the resolution 8×8. No matter which way I get it in this resolution, it just won’t display anything.

I tried exporting from Final Cut Pro and resizing the video with FFMPEG, but both just produce a black screen when played in QuickTime.

I’ve also tried some other media players and they work flawlessly.

Could there be any reason for that?

Here are some of my specs: MacBook Air 2019 (8GB of Ram, 1.6 GHz Dual-Core Intel Core i5), macOS BigSur 11.4 Beta