The intention was just for a white plastic and a metallic core. It appears that this worked for the first half of each polygon, but not for the last half. This issue affects all materials and shaders. For some bizarre reason, Cinema 4D R20 does not have this issue.
AMD Reference Radeon VII (using Vega 10 drivers)
Apple Mac mini i7-8700B with 32GB running macOS Mojave 10.14.4 beta 5 (18E215a)
Razer Core X eGPU enclosure