Customer's Nearest Neighbours by Revenue

Hi, 

I am not sure how your semantic model looks like, but I tried to create a sample pbix file like below.

Please check the below picture and the attached pbix file.

WINDOW function (DAX) - DAX | Microsoft Learn

expected result select: =
VAR _Slicer =
    MAX ( 'Customer slicer'[Customer Name] )
VAR _T =
    ADDCOLUMNS (
        ALL ( Data[Customer ID], Data[Customer Name] ),
        "@Revenue", [Revenue total:],
        "@SelectedRevenue", CALCULATE ( [Revenue total:], Data[Customer Name] = _Slicer, REMOVEFILTERS () )
    )
VAR _Diff =
    FILTER (
        ADDCOLUMNS ( _T, "@Diff", ABS ( [@Revenue] - [@SelectedRevenue] ) ),
        Data[Customer Name] <> _Slicer
    )
VAR _NearestCustomer =
    SUMMARIZE (
        WINDOW ( 1, ABS, 4, ABS, _Diff, ORDERBY ( [@Diff], ASC ) ),
        Data[Customer Name]
    )
RETURN
    CONCATENATEX (
        FILTER ( Data, Data[Customer Name] IN _NearestCustomer ),
        Data[Customer Name],
        " ,"
    )