Yes that fixed the export for me. 🙂
The files type selector only seems to affect the list of files displayed and not the type of being created.
no matter what you select in "Files of Type:"
The type of file created is determined by the extension on the file name no matter what you select in "Files of Type:"
e.g.
This is not as intuitive as it could be; most other programs generally use the drop down to default/determine the file type being create.