Object flattened when setting parent

I have a working IK animation using some curves. Now I am trying to animate an object by setting a moving curve as its parent. When I do, the object gets flattened to the same plane the curves exist on. Any ideas why this is happening? This is the same workflow I followed for animations in the past and I have not run into this problem before.

Before “Set parent”

After “Set Parent”. Note that when it does this, the command bar in Rhino displays “Creating meshes… Press Esc to cancel”

Can you please send me an example model and steps how to recreate this scenario on my machine?