Phantom Prims in Linked Sets

I'm building an elevator as a learning exercise. Its working fine, but as part of the exercise I wanted to alter the size of the button control panel, based on the number of floors the elevator goes to.

I do this using llSetPrimitiveParams([PRIM_SIZE, <depth, width, height>]); in the control panel itself, which is a child prim in the set.

Sometimes, apparently at random, this causes the root prim to turn phantom!

The editable properties of the root prim do not seem to change, but it clearly is phantom, even if I unlink the whole set this prim is clearly phantom but not according to the properties in the edit panel.

I understood that you couldn't have one prim in a linked set phantom, and I also can't see why this should happen.

Can someone give me a clue as to what is going on, please.

Sounds like a bug to me.

I have seen prims (and even parts of prims ) turn phantom in a linkset where everything else is solid. The solution is usually to replace the offending prim (though perhaps taking into inventory and re-rezzing might help). Not sure how this applies to your problem but might be some useful background info.