"That's strange. I used MLPro for all of Antonia's JCMs, and never had a problem."

Well, MLPro sorta works for "simple" fixes that don't require much "un-crumpling" like the usual too-high armpits or bulgy shoulders.

But try to fix a more radical "leg behind the head" or a "full split" pose for a less than stellar rigged figure, and MLPro turns out to be pretty useless in Poser.

I usually spent more time trying to "re-fix" the MLPro "Fix morph" with the morphbrush in Poser than it took to make the fix in ZBrush in the first place.
In all cases the MLPro fix looked perfect in Studio, but was a lot worse once I exported to Poser.

Remember not all figures are rigged as well as Antonia, so fixing them usually takes a lot more morphing.  ;-)