Sheet Metal - Lofted Cone or Revolved Cone, Unfold and can't Fold

Hello

I work extensively with sheet metal and have recently come across this problem.

Wether I create a cone using the

- lofted bends (sheet metal)

- revolve, (then insert bend feature to make a sheet metal part)

I can insert an unfold feature then it will not let me unfold... I can unsupress the flat-pattern feature to get the correct flat.

I would like to create a cutout when flat, display it when its folded.  I know I could wrap a sketch and do a normal cut, but either I must be doing something wrong, or there is a bug.  I have successfully done this on other parts, but I can't say i have done this with a cone.  Has anyone experienced this before?

Any help would be appreciated.