Sorry for the thread necro.  Running into the same problems.  With script, Prop will parent to a body part but doesn't show as part of the figure.

Furthermore, parenting a prop to another prop (both standalone), the prop is parented but it isn't really "connected" in the scene.

Open the hierarchy editor and the props are still at the bottom, nothing parented.  In both cases.  Also filed a report.

This makes it seriously troublesome to do other things via python once you've used SetParent.  You begin to get Nonetype references if you delete the figure and used SetParent to parent a prop.  Eventually this gets fairly unstable.

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