Cycles. Why do I see black spots instead of Lens Flares?

Please increase the value of Transparent Light Paths in the Render Properties panel to allow Cycles to properly handle the transparent elements of Lens Flares. There is no absolute correct value, as this depends on how many elements your Lens Flares have (Ghosts and Sunbeams require more transparency layers) and the type of scene you are working with. Therefore, we recommend entering the minimum value necessary to eliminate the black spots.

Lens Flare Transparent Light Path