Steps to Reproduce
  1. Create a Niagara system with two fountain emitters
  2. Replace one of the emitter's sprite renderer with a mesh renderer
  3. Set the mesh to 1M_Cube
  4. Enable Material Overrides
  5. Set the mesh emitter's spawn rate to 3
  6. Create a new material 
  7. Set the material's blend mode to Translucent
  8. Mark its usage for Niagara sprites and meshes
  9. Make a constant value and link it to the material's opacity. Set its value to .8
  10. Make a vector 4 constant and set its value to some shade of red, and pass that to the material's emissive color
  11. Assign this material to both emitters
  12. Add the system to a level
  13. Add or update an existing Post Process Volume
  14. Set its Translucency type to Ray Traced
  15. Enable all Ray Traced Translucency settings

RESULT:

When ray traced translucency is enabled, the meshes will be rendered completely black. Increasing the Max Refraction Rays has no effect. Disabling refraction will render the meshes normally. Changing the Refraction setting of the material will cause its color to change, but it does not refract like a Static Mesh in the level with the same material applied

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Unresolved
ComponentUE - Rendering - Niagara
Affects Versions4.275.0
Target Fix5.2
CreatedDec 2, 2021
UpdatedAug 25, 2022