I feel your pain. After countless tries was able to open TT Premier on my Mac (Big Sur) by setting up a new user. Jumped for joy until I tried to back up file. Error message says file is locked and unable to save. Have tried the fixes I’ve read about but nothing works. Don’t want to put in more time if I can’t save the file and who knows if I’ll be able to file electronically. The tech told me TT2021 wasn’t supported by Big Sur which is clearly untrue. Very disappointing as I’ve been using TT for years. Had similar problems last year.
