I have a mix shader combining together two sub-shaders (also mix shaders) with an alpha map like so.
But when the eye_shader is applied to an object, the area that should be covered by the iris_shader is blank white.
If I apply either one or the other of the two sub-shaders directly to an object, they render as expected.
iris_shader:
eye_background:
The alpha map is a simple transparent png with a black area.
I don't understand how the iris_shader can render as blank in the mix shader when it works fine on its own.