I found a solution, reset the SMC...
The link below is the solution for two of my issues which seems to do with the T2 Security Chip. One is this post about Encrypted external drive not accessible after Big Sur upgrade from Catalina and another issue (I did not post) I just encountered when trying to unlock System Preferences to administer users in Users & Groups. This occurs when clicking on the pad lock and enter the password to make changes.
Link to solution-
https://support.apple.com/en-us/HT203127... "If you can't unlock settings in System Preferences"
Link to Reset SMC (T2 chip): https://support.apple.com/en-us/HT201295
I am glad this information is in the support pages. I like Apple to also add to the support article that it also affects access to encrypted drives. It would help in searching for that solution.
My product info: 2018 MAC Min Catalina updated to Big Sur 11.1.