I just bought Dem Earth 3 yesterday and have been using it no problem. Today I needed to create terrain from places in Alaska, USA and when I put in the city or coordinates nothing in Alaska shows up. I'm able to use the map loader to get texture but its only on a flat plane for some reason it wont build up the geometry. Any help would be useful hopefully sooner than later im up against a deadline.
Try switching the data-set to 30 meters. If you need better data, I can provide custom 5 or 10 meter data for many parts of the USA.