I have the same question. You can't turn in a design to get a permit without exterior elevations. I have watched a video online and it suggests manually using the point to point dimension tool and it sounds like it is hit or miss on catching the floors and roof line. I tried it and it completely ignores my roof line (ridge). Why would they not give us the "Auto Exterior Dimensions"?
I hope I am missing something.
Using Home Designer Pro 2020