Aerial Dream is in 4K

I had the same issues with Aerial Dream, so now I use the plainly-named Photo Gallery and Screensaver:

https://play.google.com/store/apps/details?id=com.furnaghan.android.photoscreensaver&hl=en_US

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I think it has what you're looking for, in addition to the Aerial screensavers.

I found the latest version of Aerial dream to have this issue so I downloaded the previous version which seems to work flawlessly, at least for me. Maybe give that one a shot.

Mapee is another, no idea if it's 4k though...

https://play.google.com/store/apps/details?id=nz.arklabs.mapee&hl=en_US

One problem with Aerial Dreams is that i cannot play my own 4k videos... That's the biggest flaw in it..