Well I got this one working by recreating the shape entirely... the curves in the picture have a great many control points, is this likely to make Loft not show its single dragging point? Once I redrew them and got the number of control points down to maybe 20 per curve, Loft behaved as I wanted, with the corners matching up and a drag point available.

I am still interested in hearing advice on this subject as this isn't the first time I have run into the twisting problem although I have no other examples just now.

thanks,
Rachel