Sorry that I am so late into looking at the question you had.

I have filed three returns where I used 2019 income for EIC and for CTC.

If there is no earned income on 2020 tax return then you cannot e-file. Using the 2019 income does not go to 1040 LINE 1 (W2) so there is no verified  earned income.

Also make sure that you are claiming both, EIC and CTC. I had to go to Form 1040 and click on CTC line to be able to claim the CTC. 

I had to mail the tax returns  attaching 2019 tax copy and 2019 W2 to avoid any verification from IRS for 2019 income.

I hope this will help you.