Environment Lighs/Shadows are gone

Hi, 

I noticed that the shadows are gone. No element shows any shadow
There is an environmental option that has a shadow to select and unselect, but it doesn't do anything...
this is happening only on this artwork, if I open another one it works normally.

Thank you
The screenshot below shows the environment without shadow, none of the elements has shadow

Do you know what is possibly going on? 

Thank you