It seems that the visual effects linked to the “Volumetric Lighting” option somehow got mixed into the “Ambient Occlusion” option.
Volumetric Lighting now does nothing, no matter what you have it set to.
However, changing the settings for Ambient Occlusion also changes effects that should be considered Volumetric Lighting (such as sunbeams/godrays, light through fog, etc).
Suggested fix: Separate the two rendering options again so that each option controls the appropriate effects.