Sometimes when you add a food to your food list, it may not appear on the meal plan dropdown menus. This may happen for two reasons.
1. You're not using the correct version of excel.
2. The formulas need to be refreshed by clicking Calculate Now on the Formulas menu in the Calculation group. (shortcut: F9). You may also try switching calculation options to Automatic, though it may slow things down further as it will continuously try to refresh.