With all your sites closed, start Get Hands While Playing. Does it read any files?
If so, the first thing I would do is clear any existing hand history files from your sites' import folders in case there is a problem with a particular file. Running through Tools > Setup Assistant > Site Configuration might be able to import and move those files, but otherwise you would need to move them manually. If there are any files please attach them to a Support Ticket
so that we can see if there is a problem in the file(s) or in the import.
If you don't have any problems with your sites closed then enable logging (Configure > Options) and restart PT4. Start playing at a single table and if you have the problem then attach the PokerTracker4.log and hand history file to a Support Ticket
so that we can see what is going on. If you don't have the problem with one table then play as few as possible to generate the problem.