Hi @eric_engineer ,
I hope you're doing well. This is an old ULP, the trick to it is to type in the layer numbers at the bottom of the two comboboxes. What you click in the comboboxes actually does nothing, you have to type in the layer numbers in the fields at the bottom.
Let me know if there's anything else I can do for you.
Best Regards,

Jorge Garcia
Product Support Specialist for Fusion 360 and EAGLE
Kudos are much appreciated if the information I have shared is helpful to you and/or others.
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