I've begun using lofted bends and seem to have discovered that the profile sketches must reside on a single plane. Is that correct? The reason I suspect this is that at one point I tried to use a 3D sketch of a spline, but I couldn't select it as one of the two profiles. The other profile was a spline but it was curved only in one plane (a 2D sketch).
Also as a side question, when was the lofted bend function added to SW. I know an engineer who never uses it even though he really should. I think he started using SW before it had many sheet metal funcions and continues to use the same old methods for designing sheet metal.