Thanks for the reply, so just to clarify, I need to remove LAVFilters / k-lite and use CCleaner, then install HVEC?
Then do I install LAVFilters or k-lite on top of that again?
Also has anyone taken a look at the other issue I mentioned?
EDIT: That has brought the videos back, but the performance is still poor when seeking, it takes several seconds to play each time I seek, and the framerate is noticeably choppier.
Also I'm glad you've shown me that I can reproduce the issue in Windows Media Player, because I'm getting the same squashed aspect ratio in Windows Media as I am in DeoVR, so this gives me an easier way to test the issue.
In PotPlayer, for instance, it just works, I get none of the performance or aspect ratio issues, and it appears to be independent of what codecs I've installed.