dstat and hawtio show ActiveMQ.DLQ size of 0 yet messages remain that cannot be purged

A process is in place whereby the messages that get sent to the ActiveMQ.DLQ are cleared out via purging through hawtio. After the broker has been running for a period of time, with 20572 messages enqueued, 20722 dequeued and 24674 dispatched from the ActiveMQ.DLQ we see a case where the reported Queue Size is say n while the actual number of browsable messages listed in the queue is m. At this point purging the queue does not remove all the messages, the count goes to 0 but messages remain.

The usage pattern is that every day in the morning we put 4000 messages in a virtual topic. this virtual topic will put the messages in two different queues i.e., 4000 in queue 1 and 4000 in queue 2. we have selector in one queue, the second queue doesn't have selector. only four Jboss nodes are connected to AMQ.