DAX Questions

Question 1 :

I think that the issue is how the TREATAS function is used for "Group" because it is attempting to filter the Location column in Consolidated (2) for "Hong Kong", "Singapore", and "Shanghai". However, when "Group" is selected, the TREATAS might not properly evaluate the aggregated locations.

You need to handle the "Group" selection explicitly by summing all locations without filtering:

SelectedCurrency = "USD" && SELECTEDVALUE(Revenue[Location]) = "Group",
CALCULATE(
    SUM('Consolidated (2)'[Amount Invoiced (USD)])
),

Updated DAX Measure:

consol Amount =
VAR SelectedCurrency =
    SWITCH(
        TRUE(),
        SELECTEDVALUE(Revenue[Location]) = "Group" || ISBLANK(SELECTEDVALUE(Revenue[Location])), "USD",
        SELECTEDVALUE(Revenue[Location]) = "Hong Kong", "HKD",
        SELECTEDVALUE(Revenue[Location]) = "Singapore", "SGD",
        SELECTEDVALUE(Revenue[Location]) = "Shanghai", "CNY",
        BLANK()
    )

VAR Amount =
    SWITCH(
        TRUE(),
        SelectedCurrency = "USD" && SELECTEDVALUE(Revenue[Location]) = "Group",
            CALCULATE(
                SUM('Consolidated (2)'[Amount Invoiced (USD)])
            ),
        SelectedCurrency = "USD",
            CALCULATE(
                SUM('Consolidated (2)'[Amount Invoiced (USD)]),
                TREATAS({"Hong Kong", "Singapore", "Shanghai"}, 'Consolidated (2)'[Location])
            ),
        SelectedCurrency = "HKD",
            CALCULATE(SUM('Consolidated (2)'[Amount Invoiced (USD)]),
                      TREATAS({"Hong Kong"}, 'Consolidated (2)'[Location])),
        SelectedCurrency = "SGD",
            CALCULATE(SUM('Consolidated (2)'[Amount Invoiced (USD)]),
                      TREATAS({"Singapore"}, 'Consolidated (2)'[Location])),
        SelectedCurrency = "CNY",
            CALCULATE(SUM('Consolidated (2)'[Amount Invoiced (USD)]),
                      TREATAS({"Shanghai"}, 'Consolidated (2)'[Location])),
        BLANK()
    )
RETURN
    Amount

Question 2: 

Create a measure to dynamically calculate the top 5 clients based on total revenue:

Top 5 Clients Revenue =
CALCULATE(
    [consol Amount], -- Assuming this is the main measure
    TOPN(5, VALUES('Clients'[Client Name]), [consol Amount], DESC)
)

Then create a Line Chart for 5-Year Trends.

Question 3:

This happens because you only have one data point for the year "2024."

You can add dummy data for example, you can add rows with zero values for each month or quarter.

or you modify your measure to fill gaps with previous data:

Fill Gaps Measure =
IF(
    ISBLANK([consol Amount]),
    CALCULATE(
        [consol Amount],
        FILTER(
            ALL('Date'),
            'Date'[Date] < MAX('Date'[Date])
        )
    ),
    [consol Amount]
)

If adding data points isn't possible, you can use a "smoothed" line chart or consider a different visualization that does not depend on continuous data (like a bar chart).