There are some technical problems with e-filing of 2019 amended returns right now. TurboTax is working on the problems. You can either wait until they fix it, or print your 2019 amended return, sign it, and file it by mail.
It was only two weeks ago that the IRS started allowing amended returns to be e-filed. The problems with e-filing of amended returns in TurboTax will probably be fixed in a few days.