Thank you, @fanfare. I simply didn't attach any Form 8606 at all for 2019 1040-X. So if I mail it in before they amend/process my 2019 taxes, will that cause any issues? I was always told not to do anything like send in a second amended tax return until they've processed my original amended return, so I'm trying to be cautious. I do still have another year before the 3-year limit to 2019 is up, so I'm hoping those 16-20 weeks of processing for my amended return will be done before then. But I have heard of nightmare stories of people's amendments taking > 1 year to process.
I've also decided to send in an 1040-X for 2021 to correct the basis information I had and hope that they don't assess me any penalties, since I didn't take any distributions or do any roth conversions.
