Ellipse 0 -73.9712 40.7831 25000
Are you set linear interpolation, not cubic for surface elevation in options? Cubic interpolation is broken somehow, but linear one seems to work correct. I made a test. Shadows of builgins on the flatted area look good. I don't know why, but shadows of the rest buildings dissapeared when I use FLT file:I already tried unfortunately to no avail. My Textures/Earth/Flat has:

ELLIPSE 500 -73.9712 40.7813 400 1200 -40 10


ELLIPSE 0 40.7798 -73.9591 11131 4967 0 15