In the Unity High Definition Rendering Pipeline, when adding Volumetric Fog, there's a checkbox to enable the Volumetric Fog, and then there's an additional checkbox to the right of it that also has to be checked to enable it. Why is there the second checkbox? It feels a bit redundant.
Initially, I didn't have the second checkbox checked (indeed, I'm not certain it was initially visible), and the Volumetric fog simply did not work. I just ran into someone else who had the same problem.