Hi there, Rasher.

I understand the importance of sending invoices to customers right away. And, I'd like to inform you that our Engineering Team is looking into issue and is working to implement a solution that will resolve this issue. 

Let me provide the workaround to send invoices to customers without deleting the unsent one. 

• You can save your invoice as a PDF and send it via email through your business or other email address.
• You can send your customer a link to their invoice through SMS or messenger service. Simply click on “save and share link” then select “copy link” and paste it into your SMS or messenger service.
• If you have a Gmail or G-suite email account, you can use the send with Gmail feature to send invoices from your own address.
• You can save your invoice as a PDF, print it, and send it to your customer via mail.

Also, if you want to receive updates regarding the issue, please contact our QuickBooks Live Team. They'll add your account to the investigation and send updates via email.

Once your customers pay what they owe, you can record the payment in QuickBooks. Check out this article as your guide: Learn how to receive and record invoice payments in QuickBooks Online.

Let me know if you have additional questions by commenting below. I'll be right here to answer your concerns.