HTTP Request to Magento not returning order contents

For my Customer Service Mentor workflow I need to retrieve order details from our Magento instance. Using the n8n Magento node to get an order only works if you have the internal database order id, which is not the same as the customer facing order number (called increment_id inside Magento).
I have code in another context that retrieves order contents using the increment_id so thought this could be adapted for the HTTP Request node in n8n. This is running without errors, but the output side of the node isn’t returning order contents. See below.
What am I missing?
TIA
Stewart