The problem appears to be that TurboTax submits its own view of your 2018 AGI regardless of what you enter to "correct" a rejected efile. If you are using the downloaded version I think you can override this internal value by changing it on the Tax History and Two Year Comparison forms (Forms View). But if you are using the online version it appears there is no way to correct it. It would be nice if someone from TurboTax support was reading this thread and actually answered the issue with something other than "try zero."
