Thanks for chiming in on this thread, CaroB_.

I've checked the status of the investigation, and it's still open. Our engineers are still working on investigating the invoicing message issue you are experiencing in QuickBooks Online. We hope to have new information for you soon.

While we're unable to provide any workarounds, I recommend contacting our Customer Care Team. They can add your company information to the affected user list. This way, you will be notified when the issue is resolved.

Here's how:

1. Click the Help icon located in the upper right-hand corner.
2. In the Help window, click the Contact Us button located at the bottom.
3. Enter your question and click Let's talk.
4. Choose either Start a chat or Call us.

If you have the new QuickBooks Assistant help update, you can follow these steps:

1. In your QuickBooks Online account, go to the Help > Assistant.
2. Type Talk to a human and proceed with I still need a human.
3. Click the Contact us link.
4. Select either Messaging or Callback.

If you have any other questions, feel free to post here anytime. Take care and stay safe!