@hborre The transparency map is not providing any color. one side of the mix closure is transparent the other side goes into the void providing a solid black color because it is rendering nothing. It's like when you have two facing mirrors and not enough glossy bounces. Eventually the renderer runs out of stuff to render and renders pure black. this will not work if you want brown lashes or any other color. I never use anything other than black for my lashes anyway unless I'm rendering a male figure.

@Miss B thanks!

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740