The fix was about shafts, not shadows.
As for this shadows issue, it happens due to rendering system. When the camera turns away from some objects, the engine stops to render those objects and therefore there's no shadows from those objects. Noticable at evening and morning because it is the time when the sun light goes through many trees, fences and other objects in the world.
It's easily reproducible with a barrel fireplace. Place a fireplace barrel, ignite it in the night, turn around away from the barrel, and the barrel will be not rendered, allowing the fireplace light to spread around. Once you turn the camera back to the barrel, the fireplace light will be interrupted with the barrel body. Turn around again and the barrel will become invisible again, and the fireplace will enlighten everything around you.