For some reason I cannot place a smart dimension between two parallel flanges.
I should note that before this started happening, I used the steering wheel to give the flanges an angle up, such that they could taper to a smaller flange, but the faces still remain parallel.
Go to Solution.
The Lock in plane option of the smart dimension is active. That's why you have the chocolate-like rectangle. To disable it, press F3 while inside the tool.