I'll be watching this thread closely. I ran into same thing trying to get a snow covered effect of a leafless hardwood tree. To duplicate problem 1) create tree 2) change trunk to whatever pleases you and set number of leaves to zero in tree lab 3) duplicate tree then back to tree lab 4) change trunk texture to simple white or snow texture 5) resize and move slightly RESULTS: trash!!! I never could get rid of huge chopped out sections. Yeah, what is happening? I moved duplicated tree to left in this image to illustrate missing sections