Another wierd error with landscape layer blends

Hey guys,

When I try to get a 3rd layer involved in the material landscape this is what happens:

I’ve set the 3 layers blends based on height( sry for the mess) :

It works fine with just 2 inputs from each layer ( such base color + roughness or base color + normal or roughness + normal) but not when I try to use all 3 of them.

Any suggestions?