Hi Charles,
I assume you are mapping your result to a Mendix object. I tried xs:dateTime, xs:time, and xs:date, none of them giving me issues that you are having. Here is a suggestion that you can try: 1. Reimport your WSDL in your Consumed Web Service Document. 2. Recreate your XML-to-Domain Mapping document.
I hope that helps, otherwise feel free to file a ticket in our system.
best regards, Faried