macOS / MBP 2017 with 560 GPU + WX 9100 + RX 580 eGPUs.
I noted previously that
In RPR 2.0.10 the SSS options work perfectly except for no method switching. (The answer was that RPR only supported Random Walk anyway which is great).
However, in RPR 2.0.15 this is no longer the case.
When turning on Subsurface Principled BSDF as before you now get a completely black Render Preview and a completely failing (transparent) Final Render.
This is a regression. It was working perfectly in the previous version!
I attach screenshot of the result and a sample file (same file as previous post about SSS methods).