The current implementation of the tlog replication might interfere with the replay of the buffered updates. The current tlog replication works as follow:
1) Fetch the the tlog files from the master
2) reset the update log before switching the tlog directory
3) switch the tlog directory and re-initialise the update log with the new directory.
Currently there is no logic to keep "buffered updates" while resetting and reinitializing the update log.