Flat pattern created is not flat

[2017406]

I converted a solid into a sheet metal, then when I unfold the sheet metal or created a flat pattern, some part of it is unfolded nicely but some part of it just turns into bananas 😭😭😭.It did not flatten it properly.

[2017406 · Accepted solution]

OK, problem found, there is an curve edge which is not tangent, probably a mistake when I am sketching. 

[TheCADWhisperer]

Are there any unresolved issues highlighted in your Timeline?

Why not model this as sheet metal from the start?