Xietor, at my computer the Kingmaker map image appears as an "Unix file" when I look at the properties. Gimp will open it and call it 'rgb image', so it is a proper image, just something amiss with some specs.
Could you please start a test game with the image that one loads from the first post's link, and confirm everything works (if you haven't done it already)? I'd do it myself but as you pointed out, we don't have access to the .map file.
