I had this same problem today.  Tried the fix “ delete the hb.db and customviews.xml from the Homebase folder & relaunch PS “ and repaired all updates.  That did not fix the problem.

I uninstalled the windows update KB5008212 Security update for windows installed 12/15/21 and now Pro Series 2020 is working again.

Pro Series, can we get an update to fix this so I can reinstall the windows security update?