We are not able to validate request XML which is of SOAP protocol against web service WSDL. But same XML is validated successfully in SOAP UI against same version of WSDL.
Noticed from ITR execution properties that, assertion is throwing below error while validating schema details.
The assertion of type "XML Validation" had outcome:
line 1, column 69 : cvc-elt.1.a: Cannot find the declaration of element 'env:Envelope'.
Since schema for envelope has not included by default by xml validation assertion, need to add this schema manually. To do this, add key and value pair in Schema section as "http://schemas.xmlsoap.org/soap/envelope/". This will add schema validation for envelop as well along with WSDL.