Custom materials' COMP textures - needs explanation!

The SDK has the following statement regarding the comp textures for diffuse_code materials:

    • Normal Roughness Metal: Normal in GA (as XZ packed), B: roughness, R: metalness. Please note that the metalness in not apply on the ground.

Everybody including me read it as “put normal’s red to comp’s green and normal’s blue to comp’s alpha”, but that just doesn’t work. Albedo texture alone works fine but as soon as I plug in the comp texture it all goes crazy. Here is my Substance preset I am using:

image

I tried different sizes/bitsizes - it just doesn’t work. Asobo, please explain what was meant under “XZ packed” statement.

Albedo only:


Comp added:

Hmmm… Just realized that this works ok with the polygons, but doesn’t work with aprons. Definitely a bug.