I do appreciate the video you've attached, Roberto Verde. 

The QuickReport will show you the list of transactions. Thus, it doesn't list what's within the transaction line item. If your class tracking is added to each line item, it won't show up. But if your class are added 1 class per transaction, the class will display on the report. 

If you still get the same thing after entering the class as a whole transaction and not on the line item, we can verify and rebuild your data. This reference will walk you through it: Verify and Rebuild Data in QuickBooks Desktop.

You can check out these articles on how to customize more on your company and financial reports. 

I'm here if you need anything else. Take care!