SoapUI 5.5.0 will not run project or suites - Toolkit not initialized error

It fails for me if I disable showing the Endpoint explorer and the startup page. It fails both on Windows 7 and Windows 10.

Tue Mar 05 19:36:57 CET 2019:ERROR:Exception during Test Execution
   java.lang.IllegalStateException: Toolkit not initialized
   	at com.sun.javafx.application.PlatformImpl.runLater(PlatformImpl.java:273)
   	at com.sun.javafx.application.PlatformImpl.runLater(PlatformImpl.java:268)
   	at javafx.application.Platform.runLater(Platform.java:83)
   	at com.eviware.soapui.impl.wsdl.panels.testsuite.WsdlTestSuiteDesktopPanel$InternalTestSuiteRunListener.afterTestCase(WsdlTestSuiteDesktopPanel.java:430)
   	at com.eviware.soapui.impl.wsdl.testcase.WsdlTestSuiteRunner.notifyAfterRunTestCase(WsdlTestSuiteRunner.java:200)
   	at com.eviware.soapui.impl.wsdl.testcase.WsdlTestSuiteRunner.runSequential(WsdlTestSuiteRunner.java:130)
   	at com.eviware.soapui.impl.wsdl.testcase.WsdlTestSuiteRunner.internalRun(WsdlTestSuiteRunner.java:94)
   	at com.eviware.soapui.impl.wsdl.testcase.WsdlTestSuiteRunner.internalRun(WsdlTestSuiteRunner.java:46)
   	at com.eviware.soapui.impl.wsdl.support.AbstractTestRunner.run(AbstractTestRunner.java:128)
   	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
   	at java.util.concurrent.FutureTask.run(Unknown Source)
   	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
   	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
   	at java.lang.Thread.run(Unknown Source)