Also getting this; seems to be when the computer goes to sleep after it is locked.
Turning taskbar off on second monitor seems to have fixed it for me, but I have also known this issue to happen on computers with 1 display.
Could try removing co-pilot from taskbar and changing the taskbar search from Search box to Search icon and label.
No official fix from Microsoft, and if you look around on the internet, you'll find people with this issue going back several months