Crash when duplicating light

Good evening. When duplicating a light source from the Game Tools > FoW > Light window, I receive the spinning wheel of death, D20Pro ceases to respond and I must Force Quit (very Jedi, I know) the program. When restarting D20Pro, an error message saying the program did not close properly, do you want to attempt recovery pops up and when the program opens, the newly duplicated light source is not in the list.

<edit> I find that I am having to Force Quit D20pro nearly every time I go into the Light Window, regardless of the action I am attempting to perform. <end edit>

I am using a 2012 Macbook Air, OS X (10.11.6), D20Pro v. 3.6.6. Thank you.