Hello!
I have a hair mesh with only two textures applied to each piece. A base color and an opacity map. I have pretty much the same texture/opacity on everything. I can however see the head part of the hair through the ponytail. In this next attached screenshot, I’ve changed the color of the ponytail to blond in order to make the issue more apparent.
See, you can see the brown head part through the ponytail. And as additional info, all of my hair parts have this same material setup:
I found someone who had the exact same issue I have. Seems they did not figure it out. Although those posts were from 2 years ago, you would think Unreal Engine developers would have fixed something like this by now? Being able to layer opacity maps seems kind of important for a game engine.