Default Blender 2.81
Suzanne head (orange), 1 subdivision applied. Multiresolution Modifier with all settings at 4 subdivs. Sculpted information.
When I go to bake the normals (onto blue head), using the Cycles Bake “Bake from Multires” only produces an all blue image texture (no normal information), however if I don’t select “Bake from Multires”, the normals are produced perfectly fine. It seems checking this would produce the opposite result.
Side question: I also tend to get miniature artifacts, like a couple small pixel patches which are neon green and create weird spots on my maps, is this ray distance related? And my normals look weird with the sRGB texture mode, are Normals meant to be used as Non-colour data?