Pretty darn strange! An enigma wrapped in a mystery?
Maybe publish an image we can scratch our heads over?
Sorry i'm out of ideas.

Oh! Maybe not. Could you put a pretty big sphere in the middle of the scene, make it a perfect mirror (mercury or chrome metal material, if you have those)? Maybe by looking at that you could see where a blueish source is located? Or maybe a flat white sphere would be more blue on one part?

Anyone else?