Hello there, @reid-mccay.
Welcome to the Community. Thanks for sharing your observation about the email invoice feature in QuickBooks Online.
I want to ensure that this unexpected behavior will be addressed quickly. I'd suggest you contact our Customer Care team. They can help you check to see what's causing this to happen and help you fix it. They can also open a case to investigate this issue further.
Here's how to contact us:
You'll be attended by our chat support agent shortly. Please be ready with your account details for quick verification.
For future reference, you'll want to connect your Gmail account to QuickBooks so you can use your Gmail address to send invoices.
I'm always around here in the Community if you have other questions about invoices, @reid-mccay. Have a great day.