Why did this materials bake result in mostly black except for one area? These are cycles materials, they have all been given an image texture node set to the same image, it has all been UV unwrapped and laid out so there are no overlapping parts, I tried flipping the normals, and recalculating the normals and flipping again, and again. After that first bake where part worked, the following bakes came out all black. I had dropped the sample number to 10 just to test, so I tried a bit higher, at 40, which is what the preview render setting is and that looks alright. Still all black.
First material was not connected to Material Output.