2020Fed/State just got rejected due to "incorrect 2019 AGI". but it is the correct AGI calculated last year. i have a copy on my desktop AND a printed copy.

i filed 2019 late (on Dec 23, 2020) and had to snail mail my filings to both Federal and the State. I have since rec'd both the 2019 Fed and State refund. So, though late, it was not contested.   i have now  just completed my 2020 filings (in June 2021), and was just rejected due to "incorrect 2019 AGI".  however, TTax autopopulated the figure, and i have a hardcopy printed confirming the AGI used. AND i have handwritten the PIN number used.    why was it rejected, and what to do?