Polygons on inner layers in footprints (fp_poly)

I’m creating footprints for microwave filters in Kicad and use fp_poly for the shapes. It works nicely on the top or bottom layer, but I can’t seem to bring a footprint in with and fp_poly on an inner layer. This is the error:

Errors were encountered loading footprints
IO_ERROR: Layer 'Inner2.Cu' in file
'/home/dlharmon/REI/orion/900/pcb/difftose/libs/hp_section.kicad_mod'
at line 29, position 10
was not defined in the layers section
from /home/dlharmon/software/kicad2/pcbnew/pcb_parser.cpp : lookUpLayer() : line 895

My current workaround is to have the inner polygons on top and manually edit the PCB file to move them to an inner. Any better suggestions? I’d be open to a bit of coding if someone could point me in the right direction. It seems the problem is that there are no inners in the layer list in the footprint browser.