I’ve been using the experimental video driver for some time to try out HDR. Fired Channels up on our main Apple TV 4K a little bit ago. It returned to the last live channel we were watching (Weather channel via TVE). Tuned quickly, could hear audio but just a black screen. I then backed out and tried two different recordings. They both had the same issue. Audio worked, but black screen. I submitted diagnostics, then went into settings and changed back to default video driver. Issue was resolved immediately. Hope it helps.
I think I have noticed this too, seems to be when the TV goes to sleep while the video player is active and then you come back?
Yep, that’s exactly the case here as well!
I was able to track this down and fix it in the latest TestFlight build.