This is how it looks in Substance Player: It looks perfect in Designer before compiling, and the sbsar looks fine in the Substance Player. It's only in Marmo and UE4 that the problem occurs.
Okay, so I tried switching the engine to SSE2 in Designer and seeing how it compiled in Designer, and it looks exactly the same. Furthermore, I created an oil drum asset and compiled the sbsar for that and it worked perfectly in Marmo and UE4. I compiled it using the D3D engine. I'm not sure how this could be a problem…