No Debug for Landscsape Auto Material

I am working with a Landscape material that I’ve built. It has 6 layers and it’s be really useful to be able to use Landscape Layer Debug as I balance out where the various textures are applied.

As far as I can tell the Landscape Layer Debug mode will only detect difference between layers which have been painted by hand. Currently shows up as one solid colour to represent all 6 layers.

Any help would be much appreciated.