KDE5 desktop stops updating during OpenGL

[Cygon]

Hi!

I recently upgraded to KDE5 and most things are working fine, but for as long as I run any OpenGL application (I think that's the root of it), my desktop stops updating.

And by "stops updating" I mean this:

• All normal windows update and work normally
  
• Everything else (desktop background, task bar, clock) becomes a static image of how it was when I first launched the OpenGL application on that day.
  
• Example:
  
  1. I launch the UE4 editor at 9:00 AM. Desktop stops updating.
     
  2. I quit it at 10:00 AM. Desktop works again.
     
  3. I do something else until 4:00 PM. I then launch UE4 editor again. My task bar will show 9:00 AM and my rotating desktop background will be those from 9:00 AM.
     

So it even remembers its "desktop screenshot" somewhere. What could this be?

System: Gentoo, Kernel 4.4.6, AMD64, desktop/plasma profile, KDE5, SDDM, nvidia-drivers.