I have the same 1040X problem in amending my 2021 tax return.
The "original amount" column (A) come from I don't know where. Then there "net changes " (B) and the "corrected amount" (C). Column (C) IS the return previously filed.
Whatever is wrong, TurboTax has not fixed it.
I also had to file an amended 2018 to attach a statement, with no change in any data previously entered in 2018 return. HOWEVER, TurboTax now shows an additional refund for 2018. The program was obviously changed by TurboTax AFTER electronically filing my return. We were never advised of any program changes. When I called, the agent started a long explanation of how TurboTax sends out notices of changes, that tax laws change, yada yada. I finally stopped the person and told her the numerical change I tracked down was based upon data in the original return and that there had been no tax law changes in the area since "the beginning of time". (The change in the amendment appears correct: the data was missed by TurboTax in filing our original return).
She said she was taking notes and would "pass it on".
