From the info you cited, it appears that TurboTax does not support e-filing 1040-X for any year prior to 2021. So your choices are to print, sign and mail your amended returns or use another tax software program.
I'm so sorry for the inconvenience. This is a question that's been asked quite a bit this year. But your info was updated 2 days ago, so you have the most current information.
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***
