I'm waving my hands to let Intuit know that we have also experienced the "delivery issue" error since March of 2021. I have spent hours on the phone with customer care and done everything they could think of to troubleshoot. Most recently (October 24, 2022) I was told that my case was escalated to engineering and that I would not receive any updates on it. They would reach out if it gets fixed. It's unacceptable to me that QuickBooks isn't reliably sending invoices for so many customers and giving us no timeline or communication on it's fix.