Photo disappears when choosing aspect ratio

I found a bug - I have a collection with photos, marked with stars, and I wanted to change the format in order to post on Instagram. When I chose the format 4:5, the selected photo vanished from the previews at the bottom of the screen. Ctrl+Z brought it back, but not with the new format of course. I reinstalled 11.3 again and am waiting for the next bugfix.