SUMMARY
When fingerprint signature is enabled there is some weird behavior when locking screen again shortly after unlock (a few seconds). On this second attempt no lock screen is shown. Instead all windows become unresponsive. I can move the mouse around, but cannot interact with any windows and controls. Keyboard input is also blocked. After a few seconds mouse and keyboard become unblocked and I can use KDE as usual.

Jounrlctl shows the following warning at about the same time:

тра 15 11:44:27 p15v ksmserver[14600]: QProcess::start: Process is already running

When I remove fingerprint signature via fprintd-delete, lock screen works as expected.

STEPS TO REPRODUCE
1. Create fingerprint signature as per https://wiki.archlinux.org/title/fprint#Create_fingerprint_signature
2. Lock screen with Meta+L shortcut
3. Unlock screen with password
4. Wait 5 seconds
5. Lock screen with Meta+L shortcut

OBSERVED RESULT
No lock screen is shown. All windows and controls become unresponsive, keyboard input is blocked.


EXPECTED RESULT
Lock screen is shown.


SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.1.0
Qt Version: 6.7.0


ADDITIONAL INFORMATION
Kernel Version: 6.8.7-arch1-1 (64-bit)
Graphics Platform: X11
Fingerprint Reader: Synaptics, Inc. Prometheus MIS Touch Fingerprint Reader