With PokerTracker 4 not running please run the Black Chip installer again and that should get things working. Sometimes after an update WPN clients will remove the hand history folder and fail to write your hand histories. That is not a PokerTracker issue and reinstalling the poker client will fix that.
If it still doesn't work after that please check that hand history files are still being saved as you play and that you have the correct hand history folder configured in PokerTracker 4:
WPN Configuration GuideIf you have any further trouble please open a
Support Ticket with your support bundle and sample of hand histories:
Tutorial: Reporting A Problem