Thanks for getting back, @Creative Pictures.

I understand that encountering runtime issues while printing invoices in QuickBooks Online (QBO) can be time-consuming. 

There are times when the browser is full of frequently accessed page resources which causes some errors or unusual responses. 

With this, we can perform some troubleshooting steps to fix them.

Let's try logging in to your QBO account using a private browser as it ignores websites from using cookies and doesn’t record any historical data. 

You can use either of these shortcut keys on your keyboard to access incognito mode:

• Safari: Control + Option + P
• Google Chrome: Press Ctrl + Shift + N
• Firefox or Internet Explorer: Ctrl + Shift + P

If you can now print or download the accurate invoice number after this, then the problem is most likely caused by your browser. You'll then clear your browser cache so the system can start fresh. If the issue persists, you may need to use another supported browser as an alternative.

Lastly, you can check out this article in case you need assistance accessing invoices so customers can pay you: Take And Process Payments In QuickBooks Online With QuickBooks Payments. 

You can drop some comments below if you have any other concerns about invoices in QBO. Please know that I'm just a few clicks away to assist you. Keep safe.