After upgrading my mac to Big Sur, all of my office 365 apps stopped working.
It seems that the upgrade borked some of the file ownership permissions.
diskutil resetUserPermissions / id -u
Ready to reset user permissions on disk1s5 (Macintosh HD)
Started verify/repair permissions on disk1s5 (Macintosh HD)
User permissions have been reset
Finished verify/repair permissions on disk1s5 (Macintosh HD)
Seems to have sorted out the issue