Volumetric lights not visible in 5.4 - sometimes they render as a square

Development Rendering
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The volumetric lights fog in Unreal 5.4 is not visible.

  1. When I render out from the movie render queue - sometimes I get big bright squares where the volumetric light fog should be.
  2. Sometimes I can see faint impressions of where the volumetric light fog should be.
  3. They are visible when I switch to pathtracer.
  4. When I turn off hardware raytracing, I am able to see one of the spot lights produce the correct volumetric fog.
  5. When I open the scene in Unreal 5.5 in displays correctly.
  6. I cannot use 5.5 because as yet the Cineware plugin does not support it.