I had the same problem with a couple of gauntlet type smart props I made for my forum comp entry... to go with a freebie sci-fi outfit I found (Iris for V4).

The gauntlets that came with the outfit were, sure enough conforming figures... but I wanted a slightly different style, so modelled some myself.

But I just went with making these smart props. Had the same issue with joint spherical fall off zones... or I guessed that was what it was.

I thought it was the inherit bends... but, in fact, I then found turning off the inherit bends didn't seem to help.

I just ended up parenting the gauntlets (which were modelled on a zero pose V4), posing V4, then unparenting... somehow the props then stayed in position. Don't ask me how.