Drawn "shapes" interact with lighting in a strange, almost photo-negative way, when "Cast Shadow" is enabled.
I drew a hexagonal shape intended as a raised-floor pedestal area, and put a brazier on each corner as a light source. When the shape does not "cast shadow", it looks about how I'd expect:
However when I enable the shape to cast a shadow, the areas on that shape that should be lit, are instead darkened. The ambient lighting of the shape does not seem affected, Note, the shadow cast by the shape, onto the floor of the room, looks how I'd want it - I just don't want the lighting on the shape itself to turn black.