Outlook Mac PDF Attachments

Running Outlook Version 16.65 (22091101) on Mac OS Monterey 12.6. PDF attachments that are over a certain period (couple of months) cannot be opened or saved. Daily emails that have a PDF and can open fine.

If I try to forward the email that have the attachments they are "greyed out" and the email will be sent without the attachment

I have temporary disabled the Antivirus but still the same issue.