In Blender 2.8, 3D Viewport shading render mode is missing. How do I get it back? I've gotten to a state where my render option in the 3D Viewport is missing. I can render just fine using EEVEE. The screenshot is missing the camera and light, but I've added those and it makes no difference. 

I've been able to use the render mode by creating a new file, and appending the old blend into that new file, but I'd really like to know how to fix it when it happens. Does anyone know what might cause this, and how to correct it?
Same thing happen to me. Try switching to LookDev and under the Lighting (drop down menu next to the Viewport Shading Button), tick Scene Lights and Scene World.