Viewport Disappeared

Hello,

I'm just using Octopus for the first time, and I'm having quite some trouble. I ran a simple test to make sure the outputs were correct, but I experienced a problem. During the optimization run, the viewport went blank. Now I can't see the individuals on the graph. I know they are still there however.  Is there a way to keep this from happening and/or to recover the graph?

I'd be happy to upload the grasshopper file. 

Geof