I have a data pipeline set up in Azure where I send messages to an IoTHub which then routes those messages to an EventHub. When I read from the EventHub using the standard EventProcessorHost method, I find that only one of the partitions is being read from. I assume that only one partition is actually having messages routed to it. I have not specified a partition key anywhere and expect that the messages would be routed to all of the partitions of the event hub using round robin (as per the documentation at https://learn.microsoft.com/en-us/azure/event-hubs/event-hubs-programming-guide).
How can I configure my setup to route messages to all partitions of the event hub?
Like I said in the comment:
Is it possible you are only receiving data from one device? IoT Hub does automatic partitioning based on the deviceId, so the partition affinity might be the cause.