Possible bug with Mule AMQP transport 3.6.2 community

Question

I've been tracking down some strange behavior and I've finally managed to isolate it, and I believe that it is a bug. To reproduce the behaviour I have created 4 test flows (in 4 different mule files):

<flow name="testhttpFlow">
    <http:listener config-ref="HTTP_Listener_AMIAB" path="/testsend" allowedMethods="GET, POST" doc:name="HTTP"/>
    <amqp:outbound-endpoint exchangeName="AMQP.DEFAULT.EXCHANGE" routingKey="masterMeep" exchangeType="direct" responseTimeout="10000" exchange-pattern="request-response" connector-ref="connector.amqp.mule.default" doc:name="AMQP-0-9"/>
</flow>

<flow name="testsendFlow" >
    <amqp:inbound-endpoint responseTimeout="10000" exchange-pattern="request-response" doc:name="AMQP-0-9" connector-ref="connector.amqp.mule.default" exchangeName="AMQP.DEFAULT.EXCHANGE" exchangeType="direct" queueDurable="true" queueName="masterMeep"/>
    <set-payload value="#[new java.util.ArrayList()]" doc:name="Set Payload to Collection"/>
    <scripting:component doc:name="JavaScript">
        <scripting:script engine="JavaScript"><![CDATA[payload.add("something1");
        payload.add("something2");
        result=payload;]]>
    </scripting:script>
    </scripting:component>
    <set-variable variableName="payloadCollection" value="#[payload]" doc:name="Set payloadCollection"/>
    <foreach doc:name="For Each">
        <choice doc:name="Choice">
            <when expression="payload == 'something1'">
                <amqp:outbound-endpoint exchangeName="AMQP.DEFAULT.EXCHANGE" routingKey="meep" exchangeType="direct" responseTimeout="60000" exchange-pattern="request-response" connector-ref="connector.amqp.mule.default" doc:name="AMQP-0-9 meep1"/>
            </when>
            <when expression="payload == 'something2'">
                <amqp:outbound-endpoint exchangeName="AMQP.DEFAULT.EXCHANGE" routingKey="meep2" exchangeType="direct" responseTimeout="10000" exchange-pattern="request-response" doc:name="AMQP-0-9 meep2" connector-ref="connector.amqp.mule.default"/>
            </when>
            <otherwise>
                <logger level="INFO" doc:name="Logger"/>
            </otherwise>
        </choice>
        <set-payload value="#[message.payloadAs(java.lang.String)]" doc:name="To String"/>
        <logger message="#[payload]" level="INFO" doc:name="Logger"/>
        <scripting:transformer doc:name="Replace array element">
            <scripting:script engine="JavaScript"><![CDATA[var payload = message.getPayload();
                var payloadCollection = message.getInvocationProperty('payloadCollection');
                var counter = message.getInvocationProperty('counter');
                payloadCollection.set(counter - 1, payload);
                result = payload;]]></scripting:script>
        </scripting:transformer>
    </foreach>
    <logger level="INFO" doc:name="Logger" message="#[payload]"/>
</flow>

<flow name="testreceiveFlow">
    <amqp:inbound-endpoint exchangeName="AMQP.DEFAULT.EXCHANGE" queueName="meep"  exchangeType="direct" queueDurable="true" responseTimeout="60000" exchange-pattern="request-response" connector-ref="connector.amqp.mule.default" doc:name="AMQP-0-9"/>
    <set-payload value="#[message.payloadAs(java.lang.String)]" doc:name="Set Payload"/>
    <set-variable variableName="subPayload" value="#[payload]" doc:name="Variable"/>
   <http:request config-ref="HTTP_Request_Polestar" path="/api/query/ServiceProxyConfigurationLookup" method="GET" doc:name="HTTP Get ConfigXml" followRedirects="true">
        <http:request-builder>
            <http:query-param paramName="ApiName" value="customer"/>
            <http:query-param paramName="Action" value="GET"/>
            <http:query-param paramName="Section" value="TestGPO"/>
        </http:request-builder>
    </http:request>
    <json:json-to-object-transformer doc:name="JSON to Object" returnClass="java.lang.Object"/>
    <set-variable variableName="serviceProxyConfigurationLookup" value="#[payload]" doc:name="Variable"/>
    <set-payload value="#[payload[0].ServiceProxyConfiguration.ConfigurationList + &quot;\nTestReceive\n&quot; + flowVars.subPayload]" doc:name="Set Payload"/>
    <logger level="INFO" doc:name="Logger" message="&quot;Configuration XML =\n #[payload]&quot;"/>
</flow>

<flow name="testreceiveFlow2">
    <amqp:inbound-endpoint exchangeName="AMQP.DEFAULT.EXCHANGE" queueName="meep2"  exchangeType="direct" queueDurable="true" responseTimeout="60000" exchange-pattern="request-response" connector-ref="connector.amqp.mule.default" doc:name="AMQP-0-9"/>
    <set-payload value="#[message.payloadAs(java.lang.String)]" doc:name="Set Payload"/>
    <set-variable variableName="subPayload" value="#[payload]" doc:name="Variable"/>
   <http:request config-ref="HTTP_Request_Polestar" path="/api/query/ServiceProxyConfigurationLookup" method="GET" doc:name="HTTP Get ConfigXml" followRedirects="true">
        <http:request-builder>
            <http:query-param paramName="ApiName" value="customer"/>
            <http:query-param paramName="Action" value="GET"/>
            <http:query-param paramName="Section" value="TestGPO"/>
        </http:request-builder>
    </http:request>
    <json:json-to-object-transformer doc:name="JSON to Object" returnClass="java.lang.Object"/>
    <set-variable variableName="serviceProxyConfigurationLookup" value="#[payload]" doc:name="Variable"/>
    <set-payload value="#[payload[0].ServiceProxyConfiguration.ConfigurationList + &quot;\nTestReceive2\n&quot; + flowVars.subPayload]" doc:name="Set Payload"/>
    <logger level="INFO" doc:name="Logger" message="&quot;Configuration XML =\n #[payload]&quot;"/>
</flow>

Originally, there was no testhttp flow. The endpoint connector in testsend flow was an HTTP connector, and that worked perfectly. Immediately I added the additional flow on the front, moving the HTTP connector to that flow, and adding the additional request-response AMQP (which is therefore held waiting for the inner AMQP request-reponses to complete) the inner AMQP request-response connections stopped working.

Now, they just hang on response, until the timeout occurs, then return with NullPayload.

This doesn't seem like correct bahaviour to me, and feels like some sort of bug to do with have two "layers" of AMQP Request-Response going on at one time.

Has anyone got this pattern working correctly?

Thanks!