Landscape issue when using blueprint brush paint layer

I’m trying to use the blueprint brush in the landscape. I added the option of Paint Layer Target, but for some reason when selecting the Rock layer of the material it paints only the normal map, and keeps the color of the grass. I even changed the color of the Rock to black to make sure it isn’t making any blends. However, if I select the Snow layer it works normally. Does anyone has any idea what it might be?