I am on SW 2016 SP4

I would like to design a conic sheet metal part (smth. similar to pressure vessel). In 3d it looks like below, and the conical edge for "Conical bodies" option is used for swept flange feature:

When I measure the upper edge, the length of it is 125 mm:

When I do a "Flat pattern" in the drawing, that edges appears to be 84 mm:

Lower edges also do not match in length. I would expect the edge of 189.2 mm to be the same length in 3d and in FP, and other edges require metal deformation, so they must be approximated (therefore the length of course must be different for these edges in 3d than in FP).

But now, none of edges match in length for 3d and the flat pattern.

What am I doing wrong? Part is attached.

Thank you for your help