After you file

I've read every post I can find and no one recommended putting zero in the the AGI box of a previous joint return? On the contrary, several posts said do not put a zero in the box. Out of shear frustration, since there doesn't appear to be any live support at INTUIT, I tried putting a 0 in the AGI box and the software would not accept it. How were you able to get yours accepted? Was it a joint return? Did you check your spouses AGI for 2020 on the IRS website? I am absolutely furious that I had to print and file my returns this year and that I could not get any Live Support from INTUIT. Any assistance would be greatly appreciated!