On current kde can't logoff user

I'm having a problem logging off from a user. Running in Virtual box.

Application Launcher -> leave -> Log Out

very occasionally it will work.

When it doesn't it leaves a black screen with an arrow in the middle.

This has been a problem for a week or so. Very rarely log off generally just shut the machine, so can't say how log the problem has been about.

I'm using the updates for Sat Nov 6 20:24:12 UTC 2021. The problem predates these.

If I press the Virtual Box host key <right ctrl> <F1> I can log on as root and see these processes still running.

Quote:

root 5498 1409 0 11:59 ? 00:00:00 /usr/libexec/sddm-helper --socket /tmp/sddm-authb09d8b20-2792-4773-b8ab-ec7b3b630340 --id 17 --start dbus-run-session /usr/bin/startplasma-x11 --user alex alex 5567 1 0 11:59 ? 00:00:00 /usr/lib64/libexec/kactivitymanagerd alex 5587 1 0 11:59 ? 00:00:00 /usr/bin/kglobalaccel5 alex 5637 1 0 11:59 ? 00:00:00 /usr/lib64/libexec/org_kde_powerdevil alex 5640 1 0 11:59 ? 00:00:00 /usr/bin/kaccess alex 5659 1 0 11:59 ? 00:00:00 /usr/bin/pulseaudio --start --log-target=syslog alex 5720 1 0 11:59 ? 00:00:00 /usr/lib64/libexec/kf5/kscreen_backend_launcher alex 5790 1 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --clipboard alex 5791 5790 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --clipboard alex 5806 1 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --seamless alex 5807 5806 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --seamless alex 5811 1 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --draganddrop alex 5812 5811 0 11:59 ? 00:00:10 /usr/bin/VBoxClient --draganddrop alex 5821 1 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --vmsvga alex 5822 5821 0 11:59 ? 00:00:00 /usr/bin/VBoxClient --vmsvga

If I kill the sddm-helper process the login screen presents itself and all the above processes are gone.

Any suggestions on what's going wrong?
Could there be a wrong permission somewhere?
Is it a VirtualBox problem.

Thanks