I had the same problem with a Big Sur installation on an external disk. Resetting the SMC resolved the issue for me:
https://support.apple.com/en-au/HT201295
mattprowse
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
Last seen
User for