Maybe it's related to the bug where the graphics engine can't handle map height of more than 128 plots. It usually just make plots with no terrain when you zoom out, but you never know if windows 10 acts differently. Try starting a game on a random tiny map and see if that works. If it does, then we know it's related to the map size. If not, then we can ditch that idea. Also try looking to see if anybody using civ4bts has a similar problem and hopefully a solution.