I am no longer able to add shared calendars to any users in my organization. I always get the following error message in Outlook 2016 when I try to accept an invitation to a shared calendar : "There was a problem connecting you to the shared calendar. Please ask the person who invited you to send another sharing invitation".
If I try in OWA, I click the "Accept" button but it doesn't do anything. Does anyone have a fix for this? Thanks.