The Gross Revenue field is just a "string" (a sequence of ASCII characters), so it will sort in character sequence order.
Unless there are changes to make this an integer (and this would likely be an issue, since there would be no currency indicator), you'll probably have to force sorting by manipulating the field via expression to be a number. If you want to do this, can you share a few exact values for Gross Revenue? (I don't have any).