My figures render with black eyes
If a figure is rendered with black eyes it's probably because one or more materials for the eyes have textures in the transmission channels. The cornea and reflection materials of V4, for example, are set to be of type Glass and the Transmissions channel should be pure white. If the there a is texture then it will look dark or even black.
The solution is to simply convert the texture to type Color and then set the color to pure white.