You have a hybrid deployment of on-premises Exchange Server and Exchange Online in Office 365.
You migrate a resource mailbox from the on-premises environment to Exchange Online.
In this scenario, users cannot automatically reserve the resource for a meeting.
The properties for the BookInPolicy, RequestInPolicy, and RequestOutOfPolicy parameters are stored in the mailbox, and they contain a Lightweight Directory Access Protocol (LDAP) path for the on-premises Exchange organization.
If you're running Exchange Server 2013, install Cumulative Update 7 for Exchange Server 2013 or a later version. For more information about Cumulative Update 7 for Exchange 2013 , see the following Microsoft Knowledge Base article:
2986485 Cumulative Update 7 for Exchange Server 2013
To work around this issue in Exchange Server 2010, reapply the booking policy settings after the resource mailbox is moved to Exchange Online.
For more information about how to set up booking policy settings for resource mailboxes, see Set-CalendarProcessing.