DAX Measure

Hi LoganFFS ,

I used some sample data on my side and tried to reproduce the issue, but it's working fine for me. I used following measures.

ClientCategorySum = 
CALCULATE(
    SUM('Trades'[adjustedgrossamount]),
    FILTER(
        ALLSELECTED('Trades'),
        'Trades'[ClientLastName] = SELECTEDVALUE('Trades'[ClientLastName]) &&
        'Trades'[Category] = SELECTEDVALUE('Trades'[Category])
    )
)

ClientCategorySumSignFilter = 
VAR SelectedSign = SELECTEDVALUE(MeasureFilter[Sign])
VAR ClientSum =
    CALCULATE(
        SUM('Trades'[adjustedgrossamount]),
        FILTER(
            ALLSELECTED('Trades'),
            'Trades'[ClientLastName] = SELECTEDVALUE('Trades'[ClientLastName]) &&
            'Trades'[Category] = SELECTEDVALUE('Trades'[Category])
        )
    )
RETURN
    SWITCH(
        SelectedSign,
        "Positive", IF(ClientSum > 0, 1, 0),
        "Negative", IF(ClientSum < 0, 1, 0),
        1
    )

expected output: 

Hope this helps. Please reach out for further assistance.

Thank you.