I have experienced this same behavior with SQL 2008R2. I have databases mirrored in high performance mode, in "disconnected" state due to some firewall changes that were applied over the weekend. Transactional replication is not ....... replicating. Replication Monitor does not readily show any problems at all but inspection of the Log Reader Agent shows the following message "Replicated transactions are waiting for the next log backup or for mirroring partner to catch up". Inserting a Tracer Token shows that transactions are not getting delivered to the Distributor. All i can figure at this point is that the database transactions are still considered 'active' until the mirror site confirms reciept, and this is preventing replication from flowing changes to the subscribers. The mirroring connection is now fixed so once the mirrors are caught up on the backlog, i hope that replication will resume 'replicating'.