data-sort breaks render function

Hi!
I have a datatable with some cells containing numbers. These numbers are formatted within a columnDefs.render function.
I have noticed that if I add a data-sort attribute to a cell the formatting done in the render function is lost, though the function is correctly executed.
Example https://jsfiddle.net/gfcm3tx0/
notice the missing data-sort on the last column, which is correctly shown. While the other two numeric columns contain a data-sort and the rendered value is somehow lost.