OK. It appears if there is another roof line directly below the roof you are attempting to place the boards on (including any roof returns), the "place under roof" option will place the boards under that roof. Not what is intended. It took me a while to figure that out. Every time I selected the place under roof, my board seemed to disappear! It was because it was being placed under the front porch roof and I couldn't see it! Not sure if there is a way to make this option work or if I will just need to do some manual calculations and settings...