I don't know if there's an easy fix for this, but the other major issue I have is that my rendered videos come out with a kind of intermittent pixelation. You can see it a bit on this clip
https://imgur.com/a/AkshV57
It's cell phone footage, in portrait, that has fine resolution when played inside and outside of reaper, but it gets wonky when rendered. Other footage using a phone renders fine. It seems to be this one clip.
Any help would be appreciated!