This problem has haunted me before, but can't find the solution again. It's happened earlier with kubuntu and now on Manjaro KDE, KDE neon doesn't have the problem for some reason. My only way to fix the right now is to op settings and go tol global hotkeys and find a command with no hotkey and then assign it to 5 and then back to none which frees up the key. I've searched through all hotkeys in all settings but can't seem to find the perpetrator.

The output from xev is the following

FocusIn event, serial 41, synthetic NO, window 0x8000001,
mode s, detail NotifyPointer

KeymapNotify event, serial 41, synthetic NO, window 0x0,
keys: 106 64 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

FocusOut event, serial 41, synthetic NO, window 0x8000001,
mode NotifyUngrab, detail NotifyPointer

i'm not really sure what it means, but it's very different from the other number keys that just output the key value correctly.

Really hope someone can help

Cheers

Jakob

This is sounding very similar to the problem described here viewtopic.php?f=66&t=155962

I have the same problem with my Swedish keyboard - but with the "9" key. I posted a new comment to that bug report as they seem to think it is not a bug...