Measure depending on filter selected

Hi karti1507 ,

According to the error message, it seems the returned data of visual exceed the maximum allowed size of '1000000' rows when you also apply the field [Product num] and [product Name] onto the visual. And there is a one-million row limit for data returned from cloud data sources with DirectQuery, which are any data sources that aren't on-premises. Please find the details in the below documentation.

One-million row limit

You can consider to create another two measures similar as below to replace the field [Product num] and [product Name] using the function CONCATENATEX, it will return less rows.

ConcatenateX in Power BI and DAX: Concatenate Values of a Column

Measure1 =
VAR _selcustnum =
    SELECTEDVALUE ( 'Table'[Customer Num] )
RETURN
    CONCATENATEX (
        FILTER ( 'Table', 'Table'[Customer Num] = _selcustnum ),
        'Table'[Product num],
        ","
    )

Measure2 =
VAR _selcustnum =
    SELECTEDVALUE ( 'Table'[Customer Num] )
RETURN
    CONCATENATEX (
        FILTER ( 'Table', 'Table'[Customer Num] = _selcustnum ),
        'Table'[Product name],
        ","
    )

Finally, you will get the result similar as below:

Best Regards