When you are using multiple monitors, you might get black boxes showing up on SlideProof panes:
If you get these, it means that you are using different display settings on your monitors.
How to solve this issue?
- Open PowerPoint
- Select "Optimize for compatibility" under Display Settings in the lower bar in PowerPoint (see screenshot below)
- Restart PowerPoint
Note: If you cannot see the "Display Settings" it means that your screens are using the duplicate function and not the Extend function.