Ray. I removed Design Extender and then reinstalled using a newly downloaded version of the extension. This didn't seem to do anything to help.
I used a comparison program and compared the previously generated files and the new ones. There doesn't appear to be any difference.
I assume I should be looking for a path issue in the files. It doesn't matter if I create a map in a sub folder or it's created in the root, I get the same results.