To fix the lighting issue from your question using the setup shown in this image, you should manually generate lighting in Unity 6.2 because the "Auto Generate" option is no longer availablel 111 2J.

### What to Do in This Scene

Open the Lighting window by going to Window > Rendering > Lighting.

In the Lighting window, locate and click

the "Generate Lighting" button (since "Auto Generate" does not exist now).

This action will bake the lighting data for your scene, making all objects and panels display their intended brightness and color (panels will appear white instead of gray) I