Hi there, @KobusS. I'm here to ensure you can successfully send your invoices with the attached documents.

We can perform basic troubleshooting to isolate the issue. Let's try accessing your account through an incognito window to rule out the possibility of a webpage issue. You can refer to these shortcut keys to open an incognito window in all supported browsers:

• Chrome: Ctrl+Shift+N
• Firefox: Ctrl+Shift+P
• Safari: Command+Shift+N

If you're able to send the invoices, clear your browser's cache. This way, you can access QuickBooks with a clean slate. You may have accumulated too much historical stored in your browser that caused this issue. You can also switch to a different supported browser to see if it has something to do with your browser.

Additionally, make sure that attachments don't contain special characters in the file name. Learn more about acceptable file types for attachments: Attachments in QuickBooks Online.

Please come back and let me know the result after the troubleshooting. I'm determined to ensure this issue gets resolved.