Reduction in MD subtraction of income from US obligations

Why does MD fiduciary turbotax 2023 reduce my income subtraction on MD 504 schedule A? (I am using desktop Windows Turbotax Business 2023 with Maryland.)

The software appropriately deducts state income tax on Feds 1041 and appropriately adds that deduction back to my MD income on MD 504 schedule A. It also subtracts my income from US obligations from my MD income (MD does not tax income from US obligations), but for some reason, it reduces that subtraction. It seems to be related to the 1041 deduction (taxes line 11). If I make no deduction on the 1041, the US obligations subtraction on MD 504 schedule A is not reduced.

Why does this happen or is this a TurboTax error?

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