The request is part of a collection, and I added a variable to the collection (tried an environment as well, no change) of host being https://. It runs fine with the url being fully specified in the request, but not when it’s {{host}}/. {{host} is specified w/o any https:// qualifiers, just server.domain.com.
In the console I see the expected POST followed by a GET which seems to generate the error "The requested resource does not support http method ‘GET’ ".