Showing Unique values based on multiple criteria

Hi nikki11 ,

I created a sample pbix file(see the attachment), please check if that is what you want.

1. Create a measure as below

Flag = 
VAR _tab =
    SUMMARIZE (
        'Table',
        'Table'[Client],
        "@assign",
            CALCULATE (
                DISTINCTCOUNT ( 'Table'[Assignment] ),
                ALLEXCEPT ( 'Table', 'Table'[Client] )
            )
    )
RETURN
    IF ( SUMX ( _tab, [@assign] ) = 1, 1, 0 )

2. Create a table visual and apply a visual-level filter with the condition(Flag is 1)

Best Regards