Answer by keeperkai2

According to the reference, Shader.setGlobal functions would only work on variables that are not exposed as a property in the property block. So what you have to do is remove the _test("_test",Float) = 0.0 line to make it work. Be sure to remake a new material, since unity will save the properties you have set on a material even when you are using a shader that doesn't have that property.