It should be
my.overlay, not
my.overaly, but I assume that is just a typo in your message.
Overlay is a flag that (if on) causes the black parts of a models skin to not be drawn.
When I tried this on a test model, the guard, the black parts of the model became transparent, just like they should.
when I set my.overlay = off; it turned back to normal.
So I was not able to reproduce your problem.
If you remove all references to my.overlay, does the model look correct?
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