Hi there, @@IT_Admin and everyone on this thread.

I'm updating this post to inform you all that the investigation about being unable to send invoices in QBO (INV-26508) is now tagged as closed and resolved. 

You should be able to utilize the e-invoice feature with no issue.

If there's anything else you need, just tag my name or click the Reply button. I'd be here to offer help. Wishing you and your business continued success!