As stated in the topic.
Note: you can see the file MyDefault.scrformat in the import dialog. You can see the .scrformat at the end of the line, which in Windows generally implies you can specify a file without extension, and it will be selected if it has that extension. For example, in LibreOffice Writer, if I type GrandCanyon in the Open File dialog, and GrandCanyon.odt is in the directory, it will select that. This was the expected behavior.
This, though, the full filename, is what it accepts.