We have this same issue. We verified our data, did the rebuild, updated QB a million times and I finally got someone on the phone who was able to figure out what was really going on. We had a prior employee who's email was still linked in our direct deposit somewhere; it was not visible to us when we logged into our Intuit account and tried to manage users, addresses, etc. It was only visible on the tech support's end in her system. Super bizarre. The 40001 error kept coming up because our primary admin email in Intuit didn't match what they were showing on their end. How this happens I have no idea. We are still waiting to resolve this with Quickbooks. It is complete nonsense.