hell, what is that? nothing changed for me here. it is still invisible. i just copied your script 1:1, tried it with fx on the skin and without - nothing.
if you could please set up a simple test cube with 2 skins, apply a shader to one of em and post it here, so i can check if it's my comp (unlikely, lion_ts has it as well), my 3dgs version (6.4 comm), my numbness or anything...
this is really frustrating me.