I'm having a few issues with KDE's lock screen and powering off my monitors. This has persisted since I installed the OS, over several versions of KDE.

If I disable the Screen Energy Saving (auto-turn off monitors) setting and let the Lock Screen turn on on a timer, everything works correctly.

My first issue:

If I enable Screen Energy Saving after 1 minute just to test, my two monitors do indeed turn off, but they cycle through their input modes, get back to HDMI, and turn right back on to show my desktop.

xset dpms force off does the same thing. Once the monitors cycle through their inputs the desktop comes back up.

Second issue:

If I have both the Lock Screen turn on on a timer and the monitors get shut off, I get a lock screen present on one of my two monitors. The password box is there, but I cannot type in it. The mouse responds, I can toggle show/hide password, but I cannot type in the box or get focus in it. Worse still, if I try to Switch to a new session (session manager set to restore previous session), it just brings me back to the lock screen.

I have to loginctl unlock-session from a tty to get back in.

1. Can anybody tell me why KDE is unable to keep my monitors off?
2. Why can't I type my password into my lock screen? To be clear, the lock screen accepts passwords fine, but after the monitors try to turn of, it stops working.

OS: Arch Linux 5.0.5-arch1-1-ARCH
GPU: AMD ATI Radeon RX 580
Monitors: Acer H236HL 2X on HDMI
DE: KDE Plasma 5.15.3

FWIW, screen locking/auto-off works in my Win10 VM with GPU passthrough, just not in the Arch host. This also works on my Kubuntu machine, which has one HDMI monitor.