Stationary Spot Lights in Forward Rendering cause artifacts when lighting transluceny set to Volumetric PerVertex NonDirectional. When the camera is moved around the object, the lit vertices flicker. Stationary Point Lights however function as expected and do not flicker.

Found in 4.21 CL# 4753647, 4.22 CL# 6574378, 4.23 CL# 6925347

Steps to Reproduce
  1. Open the Editor and Enable Forward Shading
  2. Create a translucent material with .5 opacity and base color
  3. Set the Translucency lighting mode to Volumetric PerVertex NonDirectional Translucency
  4. Place a sphere into the scene and scale it up a bit
  5. Aim the spot light at the sphere, bake lighting, and rotate the camera around

The Sphere will flicker and artifact

The sphere would be lit appropriately as it is with other light sources

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Won't Fix
ComponentUE - Rendering
Affects Versions4.214.224.23
CreatedJun 14, 2019
ResolvedAug 27, 2021
UpdatedSep 19, 2021