Create api connector from wsdl throws Missing property portName

When creating a custom api connector from http://www.dneonline.com/calculator.asmx?WSDL
Trying to save, it fails with "Please check your sorting arguments" in the UI and the following error in server log.

java.lang.IllegalArgumentException: Missing property portName
        at io.syndesis.server.api.generator.soap.SoapApiConnectorGenerator.lambda$createConnector$2(SoapApiConnectorGenerator.java:88) ~[server-api-generator-1.13.0.fuse-7_10_2-00008-redhat-00001.jar!/:1.13.0.fuse-7_10_2-00008-redhat-00001]

Workaround:
In "Specify service and port" screen, click the "Port" select input and select other value, then select "TestWebServiceSoap12" back, then proceed and save the api connector.