Well, then your map has brocken background polygon. The same problem happens, if you compile from osm and use --transparent, or put transparent 0x4b into the Typfile. Therefore clearly something is broken in your mp file. I also had many contourline maps, that I converted from .img to mp with gpsmapedit (to delete problematic lines), and then recompiled with mkgmap. And it does not matter which version of mkgmap. They don’t shown any probs in Mapsource 6.16 or Basecamp 3 even though compiled from mp.
