Unable to snap Okular to one half of the screen

Hi, I’m using Okular (installed as a flatpak) on Linux Mint Cinnamon.

I can’t limit Okular to half of the screen by dragging it to a screen edge. I can only set it to fullscreen when it already currently was in fullscreen, but limiting it to one half of the screen (left, right, top, bottom) doesn’t work.

All other flatpak apps (including KDE ones) work just fine, though.
(Update: That’s not true. Some other apps like KeepassXC and Discord have the same problem, but the other KDE apps I tested work.)

Do you think that’s a bug or is there some reason for this?

It looks to me like a bug with Cinnamon, specifically with its window manager. On Plasma (with Kwin) everything works as expected regarding that.