Rank a search result by the sum of amount, grouped by item.
Solution:
As you are aggregating the results (MIN, MAX, SUM etc) you also need to aggregate the expression in the ORDER BY clause, so that the results returned by the ROW_NUMBER() function match up with the summarized results of the rest of the saved search. All you would need to do is add a SUM() around {amount}:
Formula(Numeric): ROW_NUMBER() OVER (ORDER BY SUM({amount}))
OR
Formula(Numeric): RANK() OVER(ORDER BY {internalid} ASC)