I'm running into a strange issue and need some assistance/guidance if possible. I'm in the process of upgrading from Exchange 2010 to Exchange 2016. Both servers are up with inbound and outbound mail flow flowing through the 2016 server. I ran the Hybrid Configuration Wizard (HCW) on the Exchange 2016 server without any errors. However, my cloud users aren't able to book on-premise room resources, whereas prior they were able to do so.
I created a test mailbox on-premise and it doesn't have an issue booking the room. I can only surmise that this is related to Exchange Online. Any thoughts? Appreciate the help in advance.