Correctly include request header in API call (Bexio)


New user here with limited technical knowhow :smiley: I started to get familiar and have built a workflow creating Bexio (accounting software) orders for new Shopify orders. Most works smoothly now (see full scenario at the bottom), but I’m struggling with a part of the workflow to create invoices from an order.

Bexio is a verified app, but the specific endpoint isn’t included as a module, so I’m writing the call myself. I’ve created a simpler scenario to focus on the problematic part - see blueprint attached.

Whenever the scenario is run, I’m getting an error [415] Could not parse the data.
The (in my opinion) exact same request from Postman works however.

Here is my scenario:

My hypothesis is that I’m incorrectly passing the header. When I remove the header (Accept: application/json) in my Postman request, I’m also getting an error 415:

Am I correction passing the header in Is something else wrong in my request that could explain the difference between and Postman?

Additional infos:

Any help is greatly appreciated!