Check your filters to make sure they're not preventing your stats being shown. HUD Options tab of hud config window. What site are you playing at? Cash or Tournament?
OK, Please enable logging, reproduce the problem by playing a few hands on a single table and submit your PokerTracker.log and PokerTrackerHUD.log files (zip/compress them first, call it logs.zip) to the Support system , and link to this thread in the reference field of the ticket so that we can investigate.
While I was waiting for your reply, I went to the "Houskeeping" section and did an "update cache". This seemed to fixe the problem. Stats are now showing and working properly.
If I encounter more problems, I will create the log and submit as suggested.