While monitoring the Post queue it is observed that though the statistic under "Transactions Posted" keep incrementing at all times, the # of messages keep incrementing as well and the backlog is 0 at all times.
A compare is running at this time.
If a compare is running at this time, then this is a normal behavior. Though the transactions are successfully posting to target, they are not yet readreleased from Post queue. Once the compare finishes, then the messages that have successfully posted would be readreleased from the queue.
If a compare is not running, please contact Support for further investigation.