I want to stop the blank grey screen from happening to you, @Moss1. So you can view the invoice details without a moment's delay. 

Good to know that you can print the sales forms transparently. Getting rid of the invoice blank grey screen is my focus here. This way, you and your customer can review the details seamlessly. 

Are you done doing the basic troubleshooting steps provided by Jonpril above? If so and the issue persists, I'd recommend contacting our Technical Support Team. They have extra tools to double-check what's causing the problem and send a ticket to our engineers for further investigation. 

1. Go to the Help menu, then click Contact Us. 
2. Type your concern in the box and tap Let's talk. 
3. Choose either Get a call or Start a chat. 
4. Complete the required data and submit the request.

Make sure to contact them within business hours to ensure a swift response.

Did you know that you can personalize your sales forms and create recurring transactions in QuickBooks? To learn more about the process, see these articles:

•  Create recurring transactions in QuickBooks
•  Customize invoices, estimates, and sales receipts in QuickBooks.

Drop a line for additional details or if you have follow-up questions about invoices. I'm happy to answer all of your questions. Keep safe, Moss1.