How to dynamically show Top/Bottom 20 Rows based off Values and Time slicer in Matrix Table

Hi, This is my sample sheet im using and this is the pbix file i have:

Basically i have a mastersheet of stores and monthly sales transactions by customers.

I want my Matrix Table to show only Top and Bottom 20 Site's sales and their top 5 customers based off the period Slicer. E.g) i select 2024 Jan to March and it would show me the top and bottom sites for 2024 Jan to March and only the top 5 customers for that time period. The Sales value should only show the store's total sales and not only just the top 5 customer's sales. 

Currently i show the top 5 customers as below and set to 1 as the matrix table measure:

Top5Customers = 
VAR CurrentCustomer = SELECTEDVALUE('test(Sheet1)'[Customer])
VAR CurrentStore = SELECTEDVALUE('test(Sheet1)'[Customer])
VAR CustomerSalesTable =
    CALCULATETABLE(
        ADDCOLUMNS(
            VALUES('test(Sheet1)'[Customer]),
            "CustomerSales", CALCULATE(SUM('test(Sheet1)'[Sales]))
        ),
        ALLEXCEPT('test(Sheet1)', 'test(Sheet1)'[Store])
    )
VAR RankedTable =
    ADDCOLUMNS(
        CustomerSalesTable,
        "Rank", RANKX(CustomerSalesTable, [CustomerSales], , DESC)
    )
VAR CustomerRank =
    MAXX(
        FILTER(RankedTable, [Customer] = CurrentCustomer),
        [Rank]
    )
RETURN
    IF(CustomerRank <= 5, 1, 0)

 I'm trying to filter top and bottom 20 customers with this table BUT it sometimes excludes stores when i pick a time period so some of the top and bottom 20 stores are not included and the table doesnt = 40 rows

TopBottomStores = 
VAR SalesPerStore =
    ADDCOLUMNS(
        SUMMARIZE('test(Sheet1)', 'test(Sheet1)'[Store]),
        "TotalSales", CALCULATE(SUM('test(Sheet1)'[Sales]))
    )
VAR TopStores =
    TOPN(20, SalesPerStore, [TotalSales], DESC)
VAR BottomStores =
    TOPN(20, SalesPerStore, [TotalSales], ASC)
RETURN
    UNION(TopStores, BottomStores)

I'm trying to show the sales volume through this measure where it show's the depicted store's overall volume and if you drill down to customers, it shows their volume as well

MEASURE-Volume = 
VAR IsCustomerLevel = ISINSCOPE('test(Sheet1)'[Customer])
VAR CurrentCustomer = SELECTEDVALUE('test(Sheet1)'[Customer])
VAR CurrentStore = SELECTEDVALUE('test(Sheet1)'[Store])

-- Calculate store total (for when not at customer level)
VAR StoreTotal =
    CALCULATE(SUM('test(Sheet1)'[Sales]), REMOVEFILTERS('test(Sheet1)'[Customer]))

-- Build ranked customer table (only in customer context)
VAR CustomerSalesTable =
    CALCULATETABLE(
        ADDCOLUMNS(
            VALUES('test(Sheet1)'[Customer]),
            "CustomerSales", CALCULATE(SUM('test(Sheet1)'[Sales]))
        ),
        ALLEXCEPT('test(Sheet1)', 'test(Sheet1)'[Store])
    )

VAR RankedTable =
    ADDCOLUMNS(
        CustomerSalesTable,
        "Rank", RANKX(CustomerSalesTable, [CustomerSales], , DESC)
    )

VAR CustomerRank =
    MAXX(
        FILTER(RankedTable, [Customer] = CurrentCustomer),
        [Rank]
    )

RETURN
    IF(
        NOT IsCustomerLevel,
        StoreTotal,
        IF(CustomerRank <= 5, SUM('test(Sheet1)'[Sales]))
    )

The relationship is seen below:

BUT - the problem as said before, is that sometimes thetable does not show all bottom and top 20 stores (40 rows) when i pick a time period. Would love to get some help and appreciate if a draft pbix file could be made, thanks