Windows 11 File Explorer address and menu bars invisible

Suddenly on one of my Windows 11 Pro systems at home the address bar and menu bar became invisible. They were there and responded to mouse clicks and I could type in the address bar. But they are invisible. The problem existed whether signed in to the console session or an RDP session.

Also, in File Explorer and on the desktop when I right clicked, the menu window appeared but was blank. I could move the cursor through it and see a change and get submenus to open but of course they too were blank. I clicked on these menus and they responded with the appropriate response depending on where the cursor was when clicked.

I tried playing with themes, display properties, I've run SFC /scannow and DISM (with the restorehealth option). The first SFC found corruption and said it fixed it. Subsequent runs have found no problems. The last thing I did was do a Reset (keeping files). Nothing I've done has made any difference.

My account has admin rights on the system. I tried signing in with another account which also has admin rights and for this account the bars weren't invisible but simply not there. I then signed out of the other account and signed back in as myself. Much to my surprise the bars are now gone for me as well! This had not happened despite multiple reboots and all else that I had done. Only after signing in with the other account and then back in as myself. I rebooted but no change.

Any ideas how to fix this one system?

Jonathan