After upgrading to latest unity (5.2.2), after baking occlusion data, the game view is dark. To be more specific it seems that the directional sun light is working, and emissive materials look fine. Just all other lights are not working. Weirdly all the other scene views look exactly correct.
With a bit more experiment: lights with shadows are simply not working in the game view. If I turn off the shadows everything is illuminated again. The directional light is fine with shadows.
Tried different bake settings. All the same. Returns to normal when clearing the baked data.