I created a closed loop cv curve by ataching 4 smaller cv curves together. I then did a Close Curves on it to make sure it was properly closed
The final 'master' curve looks perfect, and if I test it by duplicating and lofting between the two, it behaves neatly as expected.
I then deleted the original pieces AND the history, and projected the master on to a nurbs surface. But, when I come to select the resulting curve-on-surface, it is 4 seperate bits of curve, just like my originals!

When I looked at the master curve in the hypergraph, I found there were sub-curves still linked to it called curveOriginal1, curveOriginal2 etc. This baffles me as I deleted the curve pieces as well as the history on the master???

Anyway, I deleted those sub-curves and re-projected, but the problem persists.
I can not work with the curve-on-surface in pieces, as when I come to duplicate and loft, everything gets mangled inside-out. No amount of rebuilding or re-attaching the curves-on-surface fixes this.

Might there be a fix for this?
If not, does anyone know where I might have went wrong, to prevent it happening again?

Thanks.

(If anyone wants to look at it, you can DL BrokenCurve.ma from
https://www.ajrwarr.plus.com/maya/
(68k) )