In my organization we gave a few users Full permissions to various shared mailboxes, one thing they do with this Full access is assign calendar permissions to their staff. At some point the ability to view what employee's have access to the calendar, through OWA, stopped working. The manager would do this by logging into OWA, Select "Open Another Mailbox" and then find the shared mailbox. Once the shared mailbox is open they will go to the Calendar and right click "calendar" then select "Permissions". Normally a pane on the right would open showing all the users who have access to the calendar and what level of permissions they have. Now it just pops up with an error that says: The Action Could not be Completed. You're request couldn't be completed. Http Status Code 500. (Photos Attached)
Through the shell I can still manage the permissions of the calendar but the manager used to be able to manage it themselves through OWA. If I assign myself full access to the shared mailbox I also experience the same issue.
I've also attached a picture of what Should be coming up.
Please help! Thank you!