Ok...Have you updated your TurboTax software to the latest release?
Click on Online at the top of the desktop program screen and then click on Check for Updates.
Current version for the 2021 TurboTax for Windows editions is 021.000.0738 (Click on Help>About TurboTax>Version)
If correct, then delete the amount paid with the extension and click on Done. Return back to Extension Payment and re-enter the amount.
If this does not correct the problem, then in Forms mode click on the Tax Payments Worksheet (Tax Payments) on the left side of the screen. Enter the extension payment on Line 9 of the Worksheet on Federal. This should transfer the payment to Schedule 3 Line 10.
