Replacing built-in shaders for terrain billboard grass.

I’ve replaced built-in shader for the Billboard grass “Hidden/TerrainEngine/Details/BillboardWavingDoublePass” by naming my shader the same way. Everything works fine inside Unity. When I do a build, however, it does not work. I use custom shaders for everything because of my own lighting model. I have hard time replacing built in grass billboard shader, and desperately need help.

Also my shader is based on the built-in shader and works fine inside unity, when I hit Play.

Shaders are only included in a build if they are assigned to a material that is used in a scene or if the shader is placed in a “Resources” folder (docs). Have you tried placing your replacement shader in the resources folder of your project?