Perhaps the IRS doesn't have you in their database if you were a dependent on someone else's return in 2019. 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 may allow you to efile with no AGI question.
If your return is rejected again, print it and mail it in. Then you'll be in the IRS database for your 2021 return.