Powder Snow fog shows the skybox instead of a solid colour with RTX/ray tracing enabled

When inside of powder snow the distance fog displays the skybox instead of a solid colour. This fog functions as intended with Ray Tracing off, with only the solid colour being displayed.

Steps to Reproduce:

1. Open any world with Ray Tracing on and with access to Powder Snow
2. Place a large cube of Powder Snow 
3. Enter the Powder Snow

Observed Results:

Instead of a solid colour being displayed as the fog, the fog is displayed with the skybox instead, giving an illusion of the Powder Snow being transparent.

Expected Results:

The Powder Snow fog should display a solid colour only, just as it works with Ray Tracing off.