Opening plan, I got 2 dbx's for "bad polylines". I got rid of hole in roof & edited the roof planes. Selected all walls & set top & bot to default. Moved roof lines to wall surfaces.The walls that were spec'd to have roof cut wall at bottom, the roof plane has to be on the inside edge of the wall, but the roof line needs to jog back to the outside surface when a colinear wall is spec'd not to have the roof cut.... (Explode an auto dormer & examine how all the parts of a dormer are defined (walls) & how the hole in roof is shaped.) That cleaned up the ceilings at the cheek walls. I got a centerline & snapped all the roof edges to that & visually confirmed that they all had the same ridge hgt. One of roof lines would not jog back to the outside where I knew it needed to be, so I had to enable "No special snapping" in the roof spec dbx in order to put the jog where I wanted it. Used the "edit wall layer intersection" tool to clean up knee wall corners. A couple walls would not finish properly, so had to drag top/bot in place. Select all walls & restore default top/bot to see what 2 they were. I got ride of the gaps in the cl'g over the stairs by assigning a cl'g surface to the roof plane.
The wall over the garage door was actually 3 walls.
Rambling, sorry.
Might be in your temporary dimension defaults? Mine look like attached image. & I usually get what you want.
It also matters where you click on the door/window where the temporary dimension appears- which side of the wall.
Even w/ that, temporary dimensions don't always behave like I think they should.
ebdesign's post in Shed Dormer Frustration was marked as the answer