The 1040-X did not eliminate the tax it only reduced the tax, i.e. taxpayer still ultimately owed and wants the overpaid credited to 2021 estimated tax. The 1040-X indicates a refund, and nothing prints in the 1040-X boxes for Line 23 even though in 1040-X input screen it is marked to credit to 2021, so nothing is happening. If you try and enter the credit in the estimated tax screen as apply to 2021 and suppress estimates, the credit show up on 1040 Line 36 and you get a red diagnostic saying the return (meaning Form 1040 not Form 1040-X) shows a balance due and a credit to next year, which can not be on the same form....obviously. It appears this simple amended return Form 1040-X can not be E-Filed.