Subsurface scattering is disabled on all OpenGL platforms despite the shaders being properly translated & OpenGL platforms supporting the relevant CPU-side APIs. This also affected Metal for the WWDC demo where it was disabled as a precaution, but will be enabled in the first working version (as it functions correctly AFAICT).
Try enabling r.SSS and using the associated debug tools to look at SSS output. On OpenGL nothing will happen, on Windows the SSS intermediate rendering will be shown.
Head over to the existingAnswerHub thread and let us know what's up.