I'm also experiencing the same issue with the setting reverting back to "On" and then generating invoices (via API) without any transaction number, which also prevents the emailing of an invoice to our customers.
Seeing this thread and the responses from Quickbooks support and the lack of urgency in fixing this important bug leaves me wondering if I should start looking for another invoicing and payment acceptance provider.
Hello FreshBooks or Stripe?!
Please fix this ASAP. This is a patch / hotfix level release issue. You're affecting a lot of people's businesses every day that you don't fix this issue. And to see that it was reported months and months before the forced roll out of the new layout, which introduced the bug. Pretty weak.
