Norton 360 backup "some files were not backed up" error

The last few times I ran a backup I get an error saying backup failed. "Some files were not backed up. Please make sure all other programs are closed and try again." I have re-started the computer and made sure no other apps / programs were running, but still get the error. I can't determine what exactly is not backed up. Never had this issue until I got a new Windows 11 machine a few weeks ago. I am using the lastest version of Norton 360 v. 22.23.1.21