Landscape Blend "white dots" error

[BioDread]

I've seen this error plenty times from the DX11 bug. Most of you here probably have already run into this. The "White Dots of Death" would be an appropriate term.
The only problem this time, is that the error also shows up on DX9 - as black dots. So there's gotta be something wrong with how I'm constructing my landscape material.

Here is a screenshot of my material at the moment. I am using 3 different textures, with 1 texture with 3 different masks on the RGB channels to act as my height map blends for the texture. It works perfectly except for when the 3 textures "meet".

[BioDread]

I think I might've solved this. Just don't use a heightmap blend for the first layer.
Results are pretty good. Onto blending normal maps!

[Tom Shannon]

You might also want to try a constant clamp, looks like it's clipping over 1.0 as the colors blend? Hard to tell without seeing how the LayerBlend function is working.

[DGUnreal]

Try using Weightmaps instead of Masks.
There is a difference between the two. :-)