You haven't told us how it is showing up or how you think it is supposed to show up, so I don't think anybody can help you unless you provide a lot more information.

How does Schedule B have anything to do with this?

Sorry this is on the 1041 shows up on the Schedule A but does not enter on line 4 when it is paid out of capital gains.  So it doesn't change Schedule B which still shows the capital gain as taxable to the beneficiaries.