When cluster balancing mode is set to OFF_WITH_REDISTRIBUTION, the messages sent by using MQTT protocol are not redistributed even when there is a subscriber connected to the topic in a different node. Therefore, the messages are dropped as there are no subscribers connected to the address where messages were sent.

The official documentation says:

If this is set to OFF_WITH_REDISTRIBUTION then like with 'OFF' messages won't be initially routed to other nodes in the cluster. However, if redistribution is configured, it can forward messages in the normal way. In this way local consumers will always have priority.

This has been tested on AMQ 7.10 (but probably it's affecting to the previous versions) and MQTT version 3.1.1.

Steps to reproduce:

1. Deploy a 2-nodes AMQ cluster and configure the message-load-balancing using the value OFF_WITH_REDISTRIBUTION
2. Ensure the cluster is configured to allow REDISTRIBUTION: configure in both nodes the generic address-setting match for "#" with <redistribution-delay>0</redistribution-delay>. Example:

   <address-setting match="#">
      <redistribution-delay>0</redistribution-delay>
      :
      :
   </address-setting>

3. Connect and subscribe a client to a topic "foo/bar/topic" on broker/node "0" using the MQTT protocol
4. Connect to the broker/node "1" and publish messages into the topic "foo/bar/topic" using MQTT protocol
5. The subscriber connected to the topic on node-0 will never receive the messages.
   1. Messages sent to the topic are dropped and lost because no subscriber is connected to the topic on node-1.

Using CORE or AMQP protocols the messages are properly redistributed to the other broker as there is no consumer in the local broker.