[Darryl Ramm]

First troubleshooting step should always be to carefully trash prefs. Start at “help us help you” up the top of every DUC web page. Reinstalling Pro Tools should be far down the list (and doing that does not trash prefs). What happens when you do that?

Be sure to try creating a new empty session not from a template.

Make sure your session is being created where you think it is not say on a removable drive (make sure you are really looking at a new session). What file system is on that drive?

If still stuck try creating a new Mac admin user account and log into that and try creating a session there (just in that users home folder on the boot drive). Create a new empty session not from a template and trash prefs again before trying.

Still stuck... What else changed? Installed or updated plugins? MacOS automatically updated?... do you have a system backup to recover to?