When will I be able to amend my 2020 tax return in TurboTax?

I filed my 2020 Tax Return in February with TurboTax Online and discovered I need to amend it.  I have been getting the "Your return isn't ready to be amended yet" message since late February.  It is April 1.  Does anyone know when I can amend my 2020 return using TurboTax online ?