Here are pictures of why render and of my scene.
3 Answers
In the shader editor under world remove an emission node if it's plugged into your world output and add light to the scene.
I was facing the same issue today, it could help to delete your background node in the world shader editor in addition to using scene lights and scene world. This makes the scene completely dark if there aren't nay existing lights.
By default 2.8 uses a built in HDR environment, that lights the scene. You can switch it off and use the scene lights and world in the viewport shading section.