I,ve seen the same thing happen in my renders, try rendering the scene twice in row, this some times changes the the shadows. From harsh cloudless sky, to overcast shadows. Or try rendering with the "apply post effects to render box" ticked. Maybe some one else can shed some light on why this happens?

Improvement means change. Change need not mean improvement.

I use Poser 12.0.757, 11.3 and or 2014, on Win10 64bit.