Thanks for dropping by the Community, @jlyda.
I'll ensure that you're able to see the email address associated with that invoices in QuickBooks Online (QBO).
Let's perform a few troubleshooting steps to get rid of the problem. To begin, access your account using an incognito or a private browser. These browsers won't save any internet files.
Here are the shortcut keys:
• Control + Option + P (Safari)
• Press Ctrl + Shift + N (Google Chrome)
• Ctrl + Shift + P (Firefox)
Once logged in, open the transactions again and check the email address if it's showing up.. If the private browse works, I recommend clearing the cache on your regular browser. Clearing your browser history, cache, and cookies can protect your privacy and see the latest information. You can also try using a different browser. Here's the link: System requirements for QuickBooks Online.
For additional reference, you can use the following article to personalize invoices in QuickBooks: Customize invoices, estimates, and sales receipts in QuickBooks Online.
Touch base with me here if you have any questions, I’m more than happy to help. Cheering you for continued success!