PgUp/PgDn don't work intermittently in Browser, Terminal Emulator programs (journalctl, man pages)
This problem came about some time before christmas 2018.
As the title suggests, for no apparent reason, the PgUp and Dn keys stop working and start working again after a few hours or after log out and back in. Shift+PgUp, to look for older commands works, as well as the NUM-block Pg keys (when NUM is deactivated). At first I thought this might be a problem within Cinnamon (on Arch), but yesterday I installed Manjaro with KDE on a laptop and got the same problem (within the X session, not wayland)
When switching to another TTY, the keys in question work as intended
I've tried to get some help on the Arch Forum, which didn't help. Then I posted a bug report on Cinnamon Github and found two other persons who have the same problem. One with Cinnamon on Mint, the other on Tumbleweed (DE not known, supposedly Cinnamon).
Arch + Cinnamon + AMD8320e + RX480 + mesa 18.3.2 + xorg-server 1.20.3
Manjaro + KDE(X) + i5 3210M + i915 + mesa 18.3.2 + xorg-server 1.20.3
Please let me know if I can supply any logs. There is no ~/.xsession-error on my system and there are no errors in the /var/log/sddm.log