On our side this problem occured as well (Error getting response for [...]; null). We could resolve it by exchanging the existing xmlsec-1.4.5.jar file contained in the /lib folder with newer version xmlsec-1.5.2.jar.
I tried that and it didn't work. However along same lines I looked at differences in the lib folder between old version which worked (4.5.0) and new version which didn't (5.1.3) and found a similar fix which did work for me:
Rename wss4j-1.6.16.jar to wss4j-1.6.16.jar.old
Copy wss4j-1.6.2.jar from same location for SoapUI 4.5 to this folder.
Restart and it works now.
I am experiencing the same issue. When I turn off incoming WSS, I get a response in the response window, but it is encrypted. With the incoming WSS setup, I get "error gtting response; null" and the response does not show in the window.
I am receiving a response with the incoming WSS setup - I can save the response to a file using the Request Properties dump location and view it. It just doesn't show in the response window. And it is still encrypted, which is useless.
I have tried wss4j-1.6.2.jar, wws4j-1.6.7.jar, and wws4j-1.6.14.jar. No luck with any of them.
I have also tried replacing xmlsec-1.4.5.jar with xmlsec-1.5.2.jar. Same issue still showing.
I am using SoapUI-Pro 5.1.2.
Any other suggestions?