A black line will appear If a Rect Light is overlapping a mesh while a Directional Light has light shaft bloom enabled. This line will originate from where the edge of the source is overlapping the mesh and extend to the edge of the Viewport. It is more visible the closer you are to it, however it flickers at distance. It will only show up at certain angles when further away.

Found in 4.20 CL# 4369336, 4.21 CL# 4541578, 4.22 CL# 4553454

Steps to Reproduce
  1. Open the editor
  2. Place a Directional Light in the level and enable light shaft bloom
  3. Place a Rect Light into the level and set their source height and width to 300
  4. Move the source so that it is overlapping any mesh
  5. Move the camera close to any point that the Rect Light source overlaps the mesh

A black dotted line will flicker on the screen originating from the point that the source meets the mesh, and will extend to the edge of the screen

No artifacts would appear

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Affects Versions4.204.214.22
Target Fix4.26
CreatedNov 9, 2018
UpdatedFeb 27, 2020