I used TurboTax Deluxe ONLINE as well, and I received the same message from the IRS. I went to the IRS website and printed out each form related to the Form 8615 for me (2019 Form 8615, 2019 Line 7 Tax Computation Worksheet, and 2019 Qualified Dividends and Capital Gain Tax Worksheet) as well as the instructions for each form. I calculated everything by hand, following the IRS instructions for 2019 from their website. I got the same exact answers as TurboTax. I'm not sure why the IRS is rejecting the return when I get the same thing manually as TurboTax, using the IRS current forms and instructions.
