If you filed late or amended your return, your correct 2018 AGI may not be in the system.
https://ttlc.intuit.com/questions/1944348-how-do-i-print-and-mail-my-return-in-turbotax-online
Note: If you mail your federal return, you will also need to mail your state return. You will not be able to e-file your state return.
https://ttlc.intuit.com/questions/3415597-what-if-i-entered-the-correct-agi-and-i-m-still-getting-an-e-file-rejec