in 17.2, the "additional" layer names are "just ignored" for any padstack layers. If you have footprint objects on specific layers you will probably need to delete those objects before being able to use the footprints in another design that does not have those layers in the cross-section. Best practice would be to "clear out" the non-default padstack layers for the exported padstacks so that they match padstacks that you would design yourself but, that isn't a requirement to get things working.
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