How many tables do you have open, and how many are you playing?
Check that your filters aren't preventing the stats showing - HUD Options tab of hud config window.
If you still can't get them to show consistantly, 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.