I have a project using Blender 2.82a. When I go to material, LookDev, rendered mode, everything is black. If I open other projects I am currently working on, material preview works fine. So I know it is not my video card. Material preview was working on this project but not now.
I checked. Strength is set to one. Attached is the material preview which is still all black. And a Cycles screen rendered view so you can actually see the project.
