Hi @johnt75 , thank you for your help, your solution is perfect.
Could you please explain why measures are evaulated for invalid combinations as well? I always thought the measure would only be evaluated for the current filter context (in the example above, this would be InvoiceId and CustomerId).
Every time I think I understand DAX, something completely changes my understanding 🙂
The measure is just evaluated for the current filter context, but that changes for each data point, either a cell in a table or matrix or a point on a chart.
As I understand it, SUMMARIZECOLUMNS generates the cross join of all values in the columns you put into the visual. It will then run any measures you add for each of these combinations. If all the measures return blank then that combination is not returned as part of the result set, but if any of the measures returns a non-blank value then it will be included.