I have a sales table with columns OrderQty and Product Key
I’ve created a measure TotalQty=SUM(Sales[OrderQty])

I want to get the Rank of each product regarding its own TotalQty value against TotalQty values of all other product

The measure Rank=RANKX(ALL(Products),TotalQty) works fine and I get the following outcome:

Now I replace TotalQty by its expression in the measure Rank:
Rank=RANKX(ALL(Products),SUM(Sales[OrderQty]))
And I get the number 1 for each line of the matrix:

This seems strange to me, since, in my understanding, TotalQty is equal to SUM(Sales[OrderQty]) and as a result should behave the same way. Do you have an explanation?

Thanks in advance.