Ready Api ServiceV Deploy as WAR not working

When I create a simple mockservice using SoapUI 5.1.3 and deploy this using War on Tomcat9 everything works fine.

Using that same project in Ready API 1.5.0 and deploying the ServiceV as a War on Tomcat9 gives me:

HTTP Status 500 - Error instantiating servlet class com.eviware.soapui.mockaswar.MockAsWarServlet

type Exception report
message Error instantiating servlet class com.eviware.soapui.mockaswar.MockAsWarServlet
description The server encountered an internal error that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Error instantiating servlet class com.eviware.soapui.mockaswar.MockAsWarServlet
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:361)
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1080)
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:75)
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:757)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1515)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)

I've tried all kinds of settings but can't get it get to work.