When you say that that the 2020 AGI not matching, but does match, is that based on your e-Filed or hard copy return matching. There are a millions of hard copy 2020 returns that have not been processed, and as such, the IRS does not know your 2020 AGI to compare a 2021 e-File value. Not sure if this is your issue, but if it is, then you have a lot of friends. This is the basis for entering $0 for the AGI in the validation step that has worked for others.
