Default reflection probe causing ambient light?

This might just be a misunderstanding on my part, but it appears that the default reflection probe is causing objects in my scene to be lit with ambient light based on the skybox.

If I use the following lighting settings:

Realtime shadow color: black
Environment Lighting Source: Color, black
Environment reflections: SkyBox
Environment reflections intensity: 1
No lights of any kind in the scene

And then bake lighting, everything gets lit based on the reflection probe. If I turn environment reflection intensity to 0, everything is black as I would expect in a scene with no lights at all.

What’s going on here? Attached is an example of what I’m seeing. There is a matte cube front, a shiny cube behind it and a textured sandy terrain. There are no lights and no ambient light. I would expect the skybox not to affect anything based on the above settings. If I create a reflection probe that encompasses the map and bake it with a solid black color, everything becomes solid black as I would expect.