How to send messages from Iot Edge Module to Storage Account through route?

I have an IoT Edge Module filtermodule which sends telemetry using send_message (docs) with IoTHubModuleClient every minute.

When I run this module, the IoT Hub message counter in the portal is incrementing. Also, I used this route in the IoT Edge Hub configuration for deployment:

"routes": {
  "filtermoduleToIoTHub": "FROM /messages/modules/filtermodule/outputs/* INTO $upstream"
}

Furthermore, I created a custom route and endpoint in IoT Hub which routes messages to a storage account (key based authentication). The route query is true and I tested the same telemetry data with the route and all tests pass in the sense that it matches the query.

I can confirm that if I use IoTHubModuleClient.create_from_connection_string(conn_string) on my local machine, the route works and data shows up in the storage account. When I use IoTHubModuleClient.create_from_edge_environment() on the IoT device within the edge environment, the route does not work (but the message counter in the portal does increment).

The same is true for monitoring events for that device in Azure IoT Explorer. When I run it locally using IoTHubModuleClient.create_from_connection_string(conn_string) I see events showing up. When I use IoTHubModuleClient.create_from_edge_environment() on the IoT device I see no events showing up. I validated that the device connection string in the iotedge config is correct.

How can I properly debug this? What am I doing wrong?