Camel concurrentConsumers does not work in Fuse

Issue

I'm using the concurrentConsumers option on a JMS consumer:

concurrentConsumers=10&asyncConsumer=true

This works perfectly as I can see in the console with the different threads being used for processing.
However when I use the exact same thing in a route that is dynamically loaded and started (my route is an XML file that I add to the context and start it) only one thread is used. Any clue on what is wrong ?