Yes if you didn't file 2018 on time the AGI is not in the right database and if they haven't processed it yet the AGI is not there at all. So you have to enter zero to efile 2019. That's common.
Do not file again. The IRS is way behind with Covid-19. Just keep waiting for both 2018 and 2019. See this IRS page for the latest information
https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue
Is 2019 showing up at IRS Where's my refund yet?
https://www.irs.gov/refunds/
Make sure you are using the refund amount from your actual federal tax return and not the combined amount Turbo Tax showed you at the end. That was for federal and state combined.
