strange SoapUI mock service response "error 500"

Hi!
I've got a strange problem - some time ago (may be month) SoapUI began to respond with error 500 instead of proper answer.
Here is the request example:

<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
   <env:Header/>
   <env:Body>
      <defaultNS1:NewOperation xmlns:bpws="http://schemas.xmlsoap.org/ws/2003/03/business-process/" xmlns:defaultNS="http://www.example.org/ExtAsynchResponse/" xmlns:defaultNS1="http://www.example.org/ExtAsynchResponse/" xmlns:ns8="http://www.example.org/ExtAsynchResponse/">
         <in>1</in>
      </defaultNS1:NewOperation>
   </env:Body>
</env:Envelope>

Note that instead of "env" "envelope" prefix can be used as well but anyway the following answer is given by the SoapUI stab:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <soapenv:Body>
      <soapenv:Fault>
         <faultcode>Server</faultcode>
         <faultstring>java.lang.RuntimeException: net.sf.saxon.trans.XPathException: XPath syntax error at char 17 in {/soapenv:Envelope/soapenv:Body}:
    Prefix soapenv has not been declared</faultstring>
      </soapenv:Fault>
   </soapenv:Body>
</soapenv:Envelope>

This very strange problem because earlier this request worked and now all SoapUI version responding this problem (4.5.2, 4.5.0, 4.0.0 versions tested) - it appears like e.g. some dynamically accessed schema has been updated and SoapUI started to repond like this since that time.
Attaching the SoapUI project to reproduce this and the WSDL which is used to generate the request and stub.
To reproduce start the ExtAsynchResponseSOAP MockService and execute the WS using either the ExtAsynchResponseSOAP\NewOperation\test1 or the test2 requests. Note that even the defaualt request generated by SoapUI automatically gives the same problem.