I have heard that probably less than 20 times out of the many many many thousands of PT4 converts we have. Universally PT4 is perceieved to be the best of breed, we are flattered by the opinions that have been shared... so when someone says PT3 was better, there is usually a bit more to the story than meets the eye.
This sounds like you are using a computer that does not meet the minimum spec requirements for PokerTracker 4. Please review the minimum required specs here -
https://www.pokertracker.com/faq/PT4#Minimum_Requirements
Users whose computers meet these specs rarely have the issues you are describing, so its a safe bet to assume this could be your problem.
Another possibility could be that you did not allow your database to update when advised by PokerTracker after installing an update. This could result in mismatched data, which could hamper your performance. We sugest clicking
Database > Database Maintenance > Rebuild Cache. This could take a while depending on the size of your database.
Blame Merge for this, not PokerTracker. The hand histories are missing many key data points needed such as the buyin the size of the sngs, the number of players, and the payout structure. We have worked with Merge to come up with a grid system that allowed us to estimate the buy in size but there was a period when this grid data was not available at all when they switched from SNG animal names, during this period no SNG data other than the hands could be detected, you were required to enter in the data manually (Tournament Edit). You can create a new database and reimport, you may find that many of the tournaments are now detectable but were not at the time that you played them.