There's a known issue regarding counter overflows in single return rows. The error is most likely with the #1 result, because when I see that 105MB == 1.91%, then ~75% should be slightly over 4GB, which is probably the correct amount for the traffic of your first result row. Check the totals, those should be correct, you should see a lot more data there than when adding up the result rows.
The internal sorting routine is not affected by the overflow, therefore the sorting works correctly.
