you may want to switch to the CD/Download version.
Note: i don't have 2019 TurboTax, but I can confirm, as you noted, your numbers are not a problem for 2018 TurboTax CD/Download.
Is your prior years basis tiny (I mean really tiny !) ?
TurboTax CD/Download will compute the basis adjustment factor to five decimal places.
Even a basis of $750 is calculated with no error.
At that scale the prorated amounts are negligible, and 8606 could be done away with.
