Bandwidth counters not working, 8.6.0

[MattS-TR]

Running Plesk Control Panel 8.6 on Windows Server 2003. All sites are showing 0.00 MB used in the traffic report. I recently went over on my bandwidth bill and went back to check, and found no data. Everything else appears to be working correctly, all services are running and as far as I can tell, all other features are operating as they should. I can't find any suggestions with Google, so any help would be appreciated.