Physical Material Mask does not return the correct value

Download the licensee repro project here - [Link Removed]

Download the licensee description of the problem here - [Link Removed]

Open the project and inspect the assigned material's Physical Material Mask and related components.

Note there are 4 components attached to the material:
Red = Metal
Green = Rubber
Blue = Cardboard
Magenta = Ice

These map to the colours of the assigned texture which has been reused for the mask.

The pointer in the map features a callable function "Event Read Phys Mat". This uses a line trace to determine the collision with the phys material, and should return the material type depending on the colour hit (e.g. if you point the arrow at blue, and press the button it should return PhysMat_Cardboard).
The actual result is PhysMat_Metal is always returned.