Thanks for being a valued customer of QuickBooks, lisaccasc.
I know this isn't the experience we want you to have. As I've checked on the current investigation, I do see here that our engineers are still working on fixing the issue. Rest assured they aren't stopping until you'll be able to send invoices to your customers.
If you haven't been added to the list of affected users, I encourage you to reach out to our QuickBooks Online Support. They'll be able to pull up your account and add you so you'll receive an email notification once it's fixed. Please follow the steps provided by RoseJillB to reach them.
In the meantime, you can consider manually downloading your invoice and sending them outside QuickBooks. You can follow the steps I outlined above.
For future reference, I'm adding this helpful article about recording invoice payments manually in QuickBooks Online: Record invoice payments in QuickBooks Online.
You're always welcome if you need further assistance with sending invoices. We're always here to lend a helping hand.
