Ray traced mirror missing fog

r.RayTracing.Reflections.HeightFog 1

I have Ray Tracing enabled for reflections. My mirror material is a very simple white Base Color, 1 Metallic and 0 Roughness.
I have an HDR and Exponential Height Fog components with Volumetric Fog enabled.

As you can see from the attached images there is no fog being rendered in my mirror!

I tried adding a Sphere Reflection component and baking reflection maps but no difference.
Since my mirror geometry is attached to a moving vehicle I have made it Movable.

The only thing disabled in my Reflection - Ray Tracing settings is ‘Include Translucent Objects’ as it introduces artifacts.

Can any Ray Tracing or reflection experts help?

322523-raytrace-reflectionsettings.jpg

How you solve the problem?