Thanks for getting in touch about this. Is any data coming into TMG Reporter?
It could be that you are hitting the data retention policy specified in Settings | Data Storage and older data is being purged from TMG Reporter's data store. See: http://support.fastvue.co/customer/portal/articles/729081-how-much-data-does-tmg-reporter-store-?b_id=1646
You can try increasing the data retention policy in Settings | Data Storage (people usually hit the size limit before the days limit), then re-import your data.
To re-import after adjusting the retention policy: 1. Go to Settings | Data Storage and note the data location 2. Stop the Fastvue TMG Reporter service 3. On the Fastvue server, go to TMG Reporter's data location 4. Delete the Data.fvfs folder as well as the Import.xml file 5. Restart the Fastvue TMG Reporter service 6. Go to Settings | Sources and re-add your TMG Server as a source.
TMG Reporter will then import your log files over again, starting with the latest logs and working its way backwards. You can see what dates have been imported in Settings | Sources.