Bug 515805

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SUMMARY
Sometimes when automatically locking the screen, the primary screen turns black with just the mouse cursor visible. Logging back into Plasma via an external screen is possible, but does not resolve this. Only a hard reset fixes the issue. 

Sometimes when turning the computer back on after such an event, the primary screen only displays the wallpaper. You cannot move windows or the mouse cursor to it. You need to open the settings to turn the primary screen off and on again. 

STEPS TO REPRODUCE
1. Connect your computer to an external monitor
2. Enable automatic screen locking
3. Place your mouse on the primary monitor 
4. Wait for automatic screen locking to engage

OBSERVED RESULT
The primary screen turns black with just the mouse cursor visible

EXPECTED RESULT
All screens should lock normally and display the login screen. They should resume normally after logging back in 

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.2
Kernel Version: 6.12.69-1-lts (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION
Graphics Processor: AMD Radeon 780M Graphics

This bug first started occuring at some point during late 2025. The second half of the bug ("primary screen only displays wallpaper" etc.) is new. It first occurred during late January or early February 2026.