Thank you for your loyalty to QuickBooks Online (QBO), @wittlane76.

Let's get your PDF invoices attached to your email so you can get back to working order.

To get started, were you able to review the options stated by my colleague IamjuViel above? If you haven't yet, please do so.

If the options were turned on, let's try sending an invoice to yourself to check if there's an attached PDF.

If there's no PDF attached to the emailed invoice, let's log in to your QBO account using a private or a different browser. It's possible that your browser stores frequently-accessed data, thus causing websites, like QBO, to act weirdly.

Here's how:

• Press Ctrl + Shift + N on your keyboard for Google Chrome and Mozilla Firefox. 
• Press Command + Shift + N for Safari. 

Once logged in, go back and try to email the invoice again to yourself to double-check.

If this works, it means that you need to clear the browser's cache so the system can start fresh. 

If they get the same result, I highly suggest contacting our Phone Support Team. This way, they can further investigate this matter and provide additional troubleshooting steps. They can also create an investigation ticket if other users experiencing the same.

If you need any additional assistance while managing invoices, you can leave a comment below. I'll be sure to get back to you. Wishing you all the best.