Why does compiled mock not provide WSDL anymore?

For our testing we run an old machine as our "mocks-server". After changes to some WSDL or schema then we upload the updated ...-soapui-project.xml file to said server and trigger a script that feeds that file to the SOAPUI war-generator and then throws the generated .war file onto a Tomcat-server which acts as our mock-server.

So far it was always possible to request the WSDL from that server by calling the basic URL with a ?WSDL at the end of the URL. For some reason since a while that doesn't seem to work anymore, even though we didn't change anything on that system, i.e. neither the war-generator nor the tomcat has changed since quite some time. 

Occasionally that is quite convenient, esp. when a new team-member joins who doesn't yet know all the services and method names etc. "by heart". I also used that request as a "ping" or livelyhood-check for the mock-server, so it's a bit annoying that this seized to work.

Any idea, why serving the WSDL doesn't work anymore? The actual mock-services still work fine, BTW! It's really only that WSDL page that is not served anymore but only yields a "404 Not found". Is that maybe some setting in the project file that could influence this? Or some option of the .war generator (even though - as I said - that hasn't been changed).