Generally, roughness in SP/SD and in UE4 are way different than each other. The result is always smoother in UE4. What I do in SD is to run the roughness into a convert to linear node right before outputting it. That said, there’s no such node in SP but the only thing being wrong here has something to do with RGB/sRGB. I don’t know what’s exactly looking different in UE4 on your side compared to SP result. Can you please let me know?