Table.Sort, unexplainable behaviour with a two-argument function

Hi WesleyS ,

Power Query has certain expectations concerning the comparer function. If you don't meet these requirements Power Query doesn't necessarily react with an error message but with a unpredictable behaviour. Randomly switching is not unusual.

The requirements for the comparer function are:

• Two parameter (a,b). You miss this requirement in your first attempt
• The sort function should compare two rows (a and b). You don't do that in attempt 1 and 2
• The sort function must return certain values: (attempt 3 does that by accident)
  • a negative number => a comes before b
  • a zero => rows are equal
  • a positive number => a comes after b
    
    

In your case it shouldn't even be necessary to use a comparer function, the following should work:

Table.Sort(#"Added Custom", {{"Sort function", Order.Ascending}})

If you absolutely need to use a comparer function, the solution should be like this one:
Table.Sort(#"Added Custom", (a, b) => Value.Compare(a[Sort function], b[Sort function]))

Hope that helps!