Usage Manager Memory Limit (1048576) reached on queue://CLAIMS_EVENTS_IN

Issue

We are seeing following log output from Fuse Message Broker version 5.5.1-fuse-03-06:

2014-07-14 11:09:20,664 | INFO  | Usage(Main:memory:queue://CLAIMS_EVENTS_IN:memory) percentUsage=137%, usage=1436633, limit=1048576, percentUsageMinDelta=1%;Parent:Usage(Main:memory) percentUsage=4%, usage=2734189, limit=67108864, percentUsageMinDelta=1%: Usage Manager Memory Limit reached. Producer (ID:xxx-39017-1405325314547-4:2:1:1) stopped to prevent flooding queue://CLAIMS_EVENTS_IN. See http://activemq.apache.org/producer-flow-control.html for more info (blocking for: 247s) | org.apache.activemq.broker.region.Queue | ActiveMQ Task-217

However, our ActiveMQ configuration has following configures:

<destinationPolicy>
    <policyMap>
        <policyEntries>
            <policyEntry queue=">" producerFlowControl="false">
                <deadLetterStrategy>
                    <individualDeadLetterStrategy queuePrefix="EXCEPTION_" useQueueForQueueMessages="true" />
                </deadLetterStrategy>
            </policyEntry>
            <policyEntry topic=">" producerFlowControl="false">
            </policyEntry>
        </policyEntries>
    </policyMap>
</destinationPolicy>
...

<systemUsage>
    <systemUsage>
        <memoryUsage>
            <memoryUsage limit="1024 mb"/>
        </memoryUsage>
        <storeUsage>
            <storeUsage limit="1 gb" name="brokerA"/>
        </storeUsage>
        <tempUsage>
            <tempUsage limit="100 mb"/>
        </tempUsage>
    </systemUsage>
</systemUsage>
...

So the producer flow control should not kick in. Why we are seeing this problem?