Forward Rendering Lightmap Density view flicker

The shaders flicker when in Lightmap Density viewmode after enabling Instanced Stereo Rendering in Project Settings > Engine > Rendering > VR 

Tested in 4.21.2 (CL - 4753647) 4.22.3 (CL - 7053647), 4.23 P6 (CL - 7948402), 4.24 (CL - 8122865) 

1. Create a Blank project
2. Enable Instanced Stereo in Project Settings > Engine > Rendering > VR
3. Change the viewmode to Lightmap Density

Expected: The view mode would show how the light is affecting the meshes in the scene

Result: The view mode has black triangles that flicker upon movement in the scene