When I add more than one image or gif to the cover screen it just shows the time/date/battery with a black background, no gif or image.
After a lot of troubleshooting I've found out I can still have 1 gif on the cover screen, but if I have 2 or more selected (doesn't matter how big, how long, even if they were in the original slideshow that worked, etc.) then they simply just don't show up. No errors or anything.
I've rebooted, tried clearing the cache and wiping the data for always on display (looks like that's the app you edit the cover screen in), and I still have the same issue.