iMac App Store pop up login window unreadable
Hi,
I have had this issue for some time now and have been dumbfounded by this one. I have a 2017 iMac running Mojave latest update. When accessing some of my apps they require a App Store sign in and I get a garbled pop up login screen. I started in recovery mode and reinstalled Mojave and applied the available updates. That did not fix the issue. See the screen shots and any help to fix this issue would be appreciated.
Thank you
Alan
iMac 27″, macOS 10.14