Sometimes, you'll run into a calculated field that is blank and didn't calculate when it was supposed to.  There is a trick to force it to recalculate.  Normally, you can edit any other field and that will cause the system to redo that calculations.  If you're in a data entry screen where all the available fields are calculated or locked/released fields (meaning you can't modify a value in them), you can still trigger the recalc by marking outliers.  All fields that are tied together with calculations will also be recalculated.

Select a field you're looking to recalc.

Click the Mark Outlier button on the toolbar.  The calculations should then be triggered.

After the calculations were triggered, click the Clear Outlier button on the toolbar.  The calculated results should still be there.  Don't forget to save!