Spline Path Texture Projection Not Working Properly

I recently discovered the ‘spline path texture projection’ method in which you choose a Landscape paint layer and assign it to your spline in order to project a textured pathway.

This is exactly what I’ve been looking for but I’m getting a strange result!
(See images attached)

Image 1:
I set up a Landscape Layer Blend and assigned the following 3 layers:

  1. top = red

  2. bottom = textured sample

  3. mypath = yellow

Image 2:
I assigned layer 3 ‘mypath’ to the spline and the result is a projected yellow path onto the red landscape. (Perfect!)

Now I want to swap out the yellow layer for the textured layer…

Image 3:
I have now swapped over layer 2 and 3 so the textured layer is now ‘mypath’ and the ‘bottom’ layer is yellow…

Surely now if I assign ‘mypath’ to the spline I should get the textured pathway?

Image 4:
The textured pathway has appeared but it is somehow under/blended with the top (red) layer?

How can I get my textured path to sit on top of the red layer?
If I move the textured layer to the top of the layer blend material, the texture covers the whole map which is not what i wanted and I dont want to have to manually paint it in.

Would really appreciate any help anyone can offer.
Apologies it was a long winded post, but hopefully my issue is clear.