Is it possible to use LandscapeGrassOutput in a Material Layer?

I’m new to UE and specifically UE5, and I’m learning how to use Material Layers.
I know that using Layered Materials is more popular, but coming from an enterprise software background, Material Layers appeals to me due to the composition-over-inheritance nature.

I’ve made pretty good progress building a landscape auto-material, but now I want to add a Material Layer for foliage, and it just isn’t working. To remove as many variables as possible, I have a new material that has nothing in it except for the Material Attribute Layers node, piped into the output. I have a single Material Layer as the material instance’s background layer. That Material Layer has nothing but a constant 1 input into a LandscapeGrassOutput node. If I put the LandscapeGrassOutput on my master Material, then it shows up, but while its in my layer it doesn’t show anything.

Is there something special I need to do for the LandscapeGrassOutput to work in a Material Layer?

My master Material
image

My Material Layer

My Material Instance

My Foliage asset

The Result

excuse the blinding green colour that I’m using for debugging lol

also for reference, here is what happens when i drop the same landscapeGrassOutput with the same foliage asset on my master material

and for kicks, here is the test of my auto-material that I’ve been working on (i need to pick better textures and values, but I’m mostly just testing to see if it works)