Curious. I cannot reproduce that problem with the shader. However since this is a world space triplanar shader with a fairly soft blend using it on a rotated cube isn’t the best use case. If you remove the rotation does it still not have any normals?
Also are you using the default Unity cube or your own mesh? The unfortunate side effect of the Surface Shader implementation is it requires valid UVs and tangents on the mesh to work. This is because, as I mentioned in the article, Unity applies the tangent to world transform to the normal direction no matter what. Basically if you apply a regular Surface shader to the mesh and some faces aren’t showing the normal, the Triplanar Surface Shader won’t either.