Maryland State Tax Standard Deduction Blank

I just received a correction from the state of Maryland for my son's state tax return. One of the errors was the standard deduction used by TurboTax for tax year 2020.  TurboTax had all blanks for the checkbox and amount which should have been about 15% of his AGI, $11,583 for line 17. This was the free edition offered by the IRS. Why is line 17 blank, when the his 1040 used the standard deduction implying the automatic use of the standard deduction of his Maryland 502?  The standard deduction box (line 17) should have been automatically checked with the amount $1737.