A Maryland resident or part-year resident is required to file an income tax return if their gross income exceeds the minimum filing level established for the tax year. For reference, the minimum filing levels for different ages and filing statuses can be found in the Form 502 instructions, and the current year's minimum filing levels can be found here.
When preparing a Maryland resident or part-year resident individual income tax return in TaxSlayer Pro, if the taxpayer is not required to file a return but files one anyway, e.g., to have tax withholdings refunded, the return that is created won't calculate any Maryland tax and also won't show any amount for either standard deduction or itemized deductions.
If the "Deduction Method" section of Form 502 has not been completed, most likely this indicates the taxpayer's gross receipts are less than the minimum filing level and they aren't required to file.
Additional Information:
Maryland Comptroller: Individual tax return instructions