Solved
SOAP Request works in SoapUI, but not in C# code
This envelope successfully contacts an API endpoint and returns data as expected. <soapenv:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchem...
Turns out the SoapUI interface had a configured "SOAP Action", that I was not adding as a header in my HTTPWebRequest. Problem solved by adding:
request.Headers.Add("SOAPAction", "http://contoso.com/queryRecordsRequest");
