Retiree Simple IRA Withdrawal

Hi, In 2021, I made a few distributions from a Vanguard simple IRA, totaling $72k. In December, I reversed one distribution transaction, in the amount of $12K. The 1099-R shows $72k distribution instead of $60k. So, in TurboTax, I created a new 1099-R. On the Vanguard form, the taxable portion of the distribution was blank, so I left it blank on the new form within TurboTax. However, TurboTax never asked for info needed to determine the taxable portion of my distribution and is reporting a taxable distribution of 60k instead of 60k minus basis. How do I get TurboTax to ask for info needed to calculate the taxable part of the distributions? Thanks.