It is a known bug which will be fixed in Syracuse 12.14.0 scheduled for January release.
Workaround is to use SoapUI to test.

Thank you, do you perhaps know How I can get the XML output in soapUI as its generated by the built in tester? I need that exact output for integration development to continue.. The XML output for the in (Developnet -> Web services - > XML) is also not whats required.

Required:

XML VIEW of WS.

I use postman and the requirements are:
WSDL
Basic Authentication
content-type
SOAPAction
Envelope

Thank you so much, was able to get the XML as indicated.