yep its a issue, to fix it you need to reset monthup and monthdn for all users
if you have ioGUi go to usersettings
select all users
click batch processing
and put SITE CHANGE %(user) STATS MONTHDN BYTES 0
under custom command
and click go
will reset all monthdn to 0
also do the same with
SITE CHANGE %(user) STATS MONTHUP BYTES 0
Hope this helps