I'll be opening a ticket as well, but wanted to see if there was quick answer someone had. We have a newly installed 8.1.1 environment, configured against the same Azure AD tenant as our 7.5.3 non-prod environment. Wa are testing 8.1.1 prior to cut over. The 7.5.3 environment works correctly, but 8.1.1 complains it can't connect to Exchange Online. I can, on the 8.1.1 environment, log on under the ARS service account (RunAs on PowerShell), which has the ActiveRoles self-signed certificate, and connect to ExchangeOnline with it, and successfully retrieve the mailbox attributes.
ARS 8.1.1 has the same consented permissions as 7.5.3
Same Admin Servers, running under the service account context
