Sometimes the IRS database does not match the AGI number that TurboTax has. That can happen when you file an amendment. This year it is also happening because the IRS is so far behind with processing 2019 returns due to the time they lost when agents could not come to work due to COVID-19.
Since filing with zero was rejected then file again but select the option that you did not file last year. The IRS does not see that question and it will allow you to efile with no AGI question.
