Tessellation material does not show up on geometry brush

I have a tessellated material that works fine on all static meshes.
But it does not work with geometry brushes. I can assign it to the surfaces, but it doesn’t show up.

As soon, as I disable ‘tessellation’ in the material, it works just fine with the brushes.

What am I doing wrong?

Ok, I found it out by myself.
In the logs I found this message:

[2017.07.25-23.34.33:736][611]LogModelComponent:Warning: Material MAT_Cave requires adjacency information because of Crack Free Displacement or PN Triangle Tesselation, which is not supported with model components. Falling back to DefaultMaterial.

Now I need to find out that this means…