Why did 40 of our old invoices pop back up as unsent?

Hello tudicontracting-,

Welcome to Community!  Sending your invoices directly from QuickBooks Online, is a great way for your customers to review their bill in a timely fashion.  It's essential that they are being received without delay.  I would be glad to provide some insight here!

Initially, I suggest clearing cache on your browser to see if you experience the same result.  If the invoices weren't received by your customers, it could be due to one of the reasons found here.  However, if the invoices have been received and paid previously, it's important to inspect them further and determine if they're possible duplicate entries.  Should you find these are duplicate invoices, you can delete them.  However, if you're not completely certain, we would be happy to work with you in real time, and ensure your books remain accurate.  In this case, I encourage you to contact our Customer Care team for personal assistance, so they can review the situation in more depth, and navigate you through the processes, so your invoices are sent and received accordingly.

If you have any other questions or concerns, please feel free to touch base with us again.  We would be glad to assist!