Some calendar appointments do not appear in Google Calendar on an Android device

Hello -

We have a situation where one of our users finds that an occasional calendar appointment is missing from his Android phone.  The appointment however is not missing from the desktop Outlook application.  Reproducing this problem has been unsuccessful.  This is not a new problem, and actually seems specific to the job position as the person before had a similar issue.  The new user has a new AD account, and mailbox.  The only similarity I can point out is that the secretary has full access to his calendar.

Environment:

Sophos Mobile On-Prem v9.6.6 (problem has existed over many versions)
On-Prem Exchange 2013
Phone: Android Galaxy S20 using Work Profile
User's mailbox is shared with his secretary and she has full access to the calendar.  She's using Outlook 365 on a desktop to manage this.  There are only a few within our organization that are setup like this who also have an Android phone.

Things we've tried:

• Clearing the Google calendar data / cache on the phone
• Reviewing the secretary's access to the calendar it looks fine
• Verified time and time zones are correct on PC's and on the phone
• Tried sending a variety of calendar invites from different source
• I'm sure there's more I'm not remembering at the moment that we've tried

Going to try removing the secretary's calendar access and see if that does anything.  Aside from that - one thing we haven't really considered until now is Sophos Mobile causing some sort of issue with this.  Since it controls the sync with the phone, and the appointments have yet to be missing from Outlook at the desktop then why not look at Sophos Mobile?

Might there be a log where this sync activity is kept on the server?

Anyone experience this problem themselves or have any suggestions on things to try?

Thanks!