The 1099R box 4 for Federal Taxes withheld get entered when the 1099R is entered.
Make sure the 1099R is entered here:
To enter pension and annuity Payments (1099-R)
• Click on Federal Taxes
• Click on Wages and Income
• Click on I'll choose what I work on (if shown)
• Scroll down to Retirement Plans and Social Security
• On IRA, 401(k), Pension Plan Withdrawals (1099-R), click the start or update button