Steps to reproduce:
- Open attached project and the scene named "Bounce Culling Demo"
- Notice that "Room A" and "Room B" are set to the layers "room a" and "room b" accordingly
- Notice that "Light A" Culling Mask are set to everything but "room b" and "Light B" Culling Mask are set to everything but "room a"
- Notice that both lights bounce still are cast together on both game objects (room a and room b) despite their Culling Mask set (see attached image)

Expected behavior:
Game object with specific layer that is set to light's culling mask should not cast the light's bounce

Actual behavior:
Game object with specific layer that is set to light's culling mask still casts the light's bounce

Reproduced with: 5.4.0b19, 5.4.0b1, 5.3.5p1, 5.3.4f1

Note: Attached image explains the issue pretty clear