When you create a recurring meeting request in a Microsoft Exchange Server 2013 environment, and there is a conflict, for example, the room is already booked, to at least one occurrence of the recurring meeting, Resource Booking Assistant (RBA) accepts the master of the meeting, but rejects at least one of its occurrences. Additionally, RBA doesn't update the meeting subject.
This issue occurs because the setting of the DeleteSubject parameter in RBA doesn't work for recurring meetings if any of the occurrences is rejected because of conflicts.
To fix this issue, install Cumulative Update 12 or a later cumulative update for Exchange Server 2013.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.