Shadow from hidden hair

giaour94_fdcc6cb22c

I'm trying to make a hairstyle by combining two different digiwigs. I want to keep the bangs from 'flora hair' for G8f and hide the rest (by setting the cutout opacity at 0). However when I do that I am still seeing streaky shadows on the figure as it most of the hair was still there (cast by the light in an HDRI setting). Anyone have any idea what might be causing this and whether anything can be done about it?