Turbotax limiting our Virginia 529 deduction

Restating my question from yesterday.  My husband contributed $4000 to each of our 4 grandchildren's 529 accounts, each with their own ID, for a total of $16,000.  Turbotax is limiting our deduction on Virginia state taxes to $12,000.  Why?  We have plenty of AGI to apply it to.  Is this a bug?