Sorry, but I'm mystified. Here are a couple of long-shot things to try. If none of these work, call TurboTax support.
Even though NJ-1040 line 31 is white, right-click it and see if Cancel Override appears in the pop-up menu. If so, click it.
If you entered medical expenses in the federal interview, open Worksheet F in forms mode and delete it. (Click Delete Form at the bottom of the window.) It will immediately be recreated, but see if that solves the problem.
If you entered medical expenses in the New Jersey interview, go back to the Medical Expenses screen in the New Jersey interview and delete the amount you entered. Then go back to the Medical Expenses screen again and re-enter the amount. See if that solves the problem.
