Hello all!  Hope you can help.  I'm running Poser 13.3 on a MacBook Pro with the latest version of Sonoma.  I upgraded from Poser 11 a few months ago and was enjoying Poser 13 until things went a little wonky a few weeks ago.  If I change the default lights to a light set from the library,  I can do it once but if I change again the entire render window goes black.  No lights.  I can add a light from the light control sphere.  The problem only happens when I change the lights  using the library 

Any help/advice would be greatly appreciated!

How are you changing the lights in the Library?  Double-clicking or check icons at the bottom of the Library?

Oh wow!  I think you may have just solved my problem!  I know double clicking adds lights.  When I undo that add and try to change using the checkmark I get the blacked out window.  Just using the checkmark from the start seems to let me change the lights no problem.  Thank you!