Shared Calendar is missing after closing Outlook

Question

XY User starts Outlook and goes to the Calendar tab and adds the calendar of XX User under Shared calendars.

The calendar is visible and the calendar entries can be seen with details.

As soon as Outlook is closed and reopened, the calendar is no longer available and must be added manually again.

The issue has been occurring since the migration from On Permisses to Exchange Online. The problem has existed for about 5 weeks.

The problem, as far as we can see, only occurs in Outlook Desktop App on a Server 2016 Terminal Server and Surface Notebook.

Steps we have already taken:

New Outlook profile and delete outlook folders in %Appdata%

New User Profile

New Remote Desktop Profile Disk

Online repair of Office

Reinstall Office

Removed and reset permission for the calendar from the Outlook Exchange Online admin center and Exchange Online PowerShell.

And we tried the above steps both with and without Cached Exchange Mode

Answer 1

I also have a client who is on O365 Apps for Enterprise having the same issue where an M365 group calendar disappears when closing Outlook. When we reopen Outlook, the calendar shows up. When we close and reopen, it does not show. This happens every other close/reopen. Troubleshooting Done: -- Tried the new Outlook Preview. The calendar shows up, but he doesn't get updated emails at all. -- Created a new outlook profile -- Updated Office -- Ran a Quick Repair So, every other time we reopen Outlook, the calendar shows up. But, every other time we reopen afterwards, it does not show. What else can I look at doing to resolve this?