You can review your entry by doing the following:

1. Click Forms located in the upper right corner of the screen
2. Scroll to Form 1099-R located on the left side of the screen
3. A pop up window will appear for you to review your entries. 
4. If the withholding amount is not shown in box 4 of the Form 1099-R, select the Close Form button at the bottom of the window
5. Click the Step-by-Step button to return to the income section of the return.
6. Click the "I'll chose what I work on" button
7. Scroll and click Update next to the IRA, 401K, Pension Plans (1099-R) to enter the tax withholding
8. Click Continue

While in the Forms mode, if the Form 1099-R does reflect a withholding amount, then chose the Delete Form button, and re-enter the information when you return to the interview section of your return.  It may be a temporary glitch in the program.