If you have a Room calendar that is not auto accepting invites do this:
Check to make sure its a Room:
get-mailbox <Identity>| fl *type*,*link*,*share*
If it's not a Room, make it a Room:
Set-Mailbox <Identity> -Type Room
Make sure its set to auto accept invites:
Get-CalendarProcessing <Identity> | fl AutomateProcessing
The AutomateProcessing attribute should be set to AutoAccept
To change it if it's not set to AutoAccept:
Set-CalendarProcessing <Identity> -AutomateProcessing AutoAccept -ConflictPercentageAllowed 0 -maximumConflictInstances 0
I got this info from KB Article 2005631 on Microsoft's Support site.
