Hello jwfitt,
Thank you for your report. We have attempted to recreate the issue that you have been having with multiple monitors and were unsuccessful.
As per following the steps listed, I opened the editor, went into my control panel and switched from 2 monitors to 1. The screen in the editor never turned black. If there are any other steps that occurred during the previous steps that you have provided, they would be beneficial in our attempt to further investigate this issue.
Thanks and have a great day!