As many people before me, I'm trying to bake a terrain texture from a Blender material for Unity, and hence not illuminated by light in the scene.
I noticed a ton of forum posts by people with similar issues, but not one of the proposed solutions worked for me. I tried piping the colour output through an emissions shader instead of the principled bdsf shader and baking as the "emit" type, but to no avail... still black. I tried a glossy bake type... black. I recalculated normals, double-checked UV map, duplicated and replaced original mesh for good measure... stubbornly black. I'm trying to do it the emission shader way, so obstruction by other objects isn't the problem.
I'm stuck, and all the internet fixes are failing.
It looks like the emission shader doesn't emit anything in the render view, which I imagine would make the bake always black. Time to investigate that!