TurboTax H&B 2022 generates incorrect 1040X!

Need to amend already e-filed and accepted return, since TurboTax doesn't have Form 8997.  Following a familiar instruction every year; no changes to any amounts, simply adding the missing form.  Starting Amended return, and immediately TurboTax shows Federal tax amount DUE!  Puzzled I open Form 1040X - the amount of previously reported AGI looks correct in Column C, but the "original amount" in Column A is totally off, and looks like some strange number, even though it's close, suddenly resulting in tax due.
This never happened to me before this year.  Is it a bug of some sort?  Has anyone else encountered it?