The numbering/positioning scheme of a Window frame seems off a bit in the sub models. There should be some way to adjust the starting node of a window frame so that the node position lines up with the actual prop. In my case I have a window with 45 nodes on the verticals and 35 nodes on the horizontal stretches. When I look at the sub model it shows 37 nodes total yet the window is specified at 35 nodes on the horizontals. My start position is bottom right, running clockwise.
Version 2018.37