Error on OAuth 2.0 connection to soaprouter
Currently still running v7, but soon migrating to v8. I've created an API connection in the Developer Console and I'm able to retrieve a fresh access token from the IMS server.
I'm trying to call the /nl/jsp/soaprouter.jsp by passing the Bearer token in the 'Authorization' header, but I keep getting 'XTK-170019 Access denied'.
My SOAPaction is set to dfn:apiCustomers#insertCustomer, which is correct.

SOAP XML is as follows

FYI, this request works 'in the old way' when I would be passing a sessiontoken. But as that will be deprecated soon, I was wondering what I'm doing wrong when trying to use Bearer token authorization.
I'd greatly appreciate your help!