The issue the vast majority have is that you create a big standard estimate. No partial invoicing, just a single estimate. You then convert it to an invoice. Even though on the invoice the custom template is selected, the invoice that gets generated is the ‘standard’ QuickBooks invoice.

The workaround seems to be to duplicate the invoice, creating a new one (unlinked from the estimate) , which then creates an invoice template properly.

Excuse my cynicism, but I don’t think you are working diligently if we have had no progress in over 8 weeks. My dev company has performed 7 ground-up signed off solutions in that time.