Bay window use existing roof broken?

[jaustin]

I've been having all kinds of odd things happen trying to put in a bay window that uses the existing roof, so I broke it down to a simple case. In this screen shot I added a bay window with default settings and then changed the angle to 35 degrees. It seems to be impossible to set the size and angle the way it's actually built without the roof doing this. This is Pro 2014.