sorry i just read that you are using P5, but i'll look at it in P6 for ya, but the results might be different, i use that skirt quite a bit and haven't noticed that before, but i usually have it semi transparent because of that deformation at the front, by default i think it comes as semi-transparent and a reflection node attached so whoever made it probally never saw any fault like that as it was meant to be see-thru and reflecting light.

 have you tried to make a uv map of it to see if there is a hole yet, not sure if it would show up like that though.

all i remember about that skirt off hand is that the skirt has three or four main material zones and then the rims, i think it shortens or sumfink in the pose settings, but i keep missing one of those rings of skirt material, so i keep getting a stripe, have you detached all nodes from all the zones to have it look like that?