It's not helpful to start over, all the people you previously interacted with lose the connection to the discussion.
Based on a quick review of the previous thread:
I will assume you started with zero balance in any traditional IRA, and that all your contributions have been non-deductible, otherwise your situation doesn't make sense.
For 2020, you made a $6000 non-deductible contribution. That should have been reported on your 2020 tax return on form 8606, even if it was made during calendar year 2021. You should have a form 8606 for 2020 that has:
Line 1 non-deductible contributions made for 2020 ....$6000
Line 2 total basis ....$0
Line 3 did you take a distribution or conversion ...No
Line 14, total basis for 2020 and before... $6000.
Then, on your 2021 tax return, you would report the non-deductible contribution of $6000. Even though you made two separate Roth conversions, they are added together and reported for 2021. (A contribution can be retroactive up until April 15, but a conversion is never retroactive, it happens when it happens.). So your 2021 form 8606 should look something like this:
Line 1 non-deductible contributions made for 2021 ....$6000
Line 2 total basis (this is your prior basis) ....$6000
Did you make a Roth conversion...Yes
Line 6 total value of all IRAs as of December 31, 2021 ...$0 (it should be zero if you did a full Roth conversion)
Line 7 distributions ...$0
Line 8 Roth conversions ...$12,000 (assuming no gains or losses)
Line 10 ...1.00
Line 11 non-taxable portion ...$12,000
Line 14 new total basis for 2021 and earlier years ...$0
From then on, your basis in the current year (line 2) is equal to your ending basis in the previous year (line 13 from the previous year). Which should be zero.
If your 2022 form 8606 shows zero basis on line 2, but a $6000 new basis on line 14, then it sounds like you didn't properly report the conversion in 2022. What are you showing on form 8606, line 8, 10 and 11? What is shown on form 1040, line 4a and 4b?
