SUMMARY
Mostly noticed after screen waking up, one screen (portrait orientation) will not show any icons in the Icons-Only or Icons-and-Test task manager.
All monitors have a task bar, and they all have the same settings, default apart from
Appearance - Un-ticked - Hide other windows when hovering over previews
Behaviour - Ticked - From current screen

STEPS TO REPRODUCE
1. Replicate settings
2. Leave to sleep for 30 mins (also happens randomly)
3. Log back in.

OBSERVED RESULT
Task manager not displaying any windows from current screen.

EXPECTED RESULT
Task manager displaying all windows from current screen.

SOFTWARE/OS VERSIONS
OS: openSUSE Tumbleweed 20240628 x86_64
Kernel: Linux 6.9.6-1-default
Shell: bash 5.2.26
Display 1: 2560x1440 @ 165Hz *
Display 2: 1920x1200 @ 60Hz
Display 3: 1920x1080 @ 60Hz
DE: KDE Plasma 6.1.1
WM: KWin (X11)
WM Theme: Breeze
Terminal: konsole 24.5.1


ADDITIONAL INFORMATION
When the problem happens, I if I toggle "From current screen", all windows appear from all screen, toggle it again, it returns blank.

If I restart the plasma session (systemctl restart --user plasma-plasmashell), everything runs as expected.

I have changed the power management to stop it going into sleep or hibernate, however it still happens, but it seems to be only after the screens are turned off and locked for 30+ minutes.