I'll share some insight on your query about transaction reports in QuickBooks Desktop (QBDT) not showing any classes, @azffs_jc.

I ran a Transaction Detail by Account in my test account and got these results. Let's take Check 476 (the first one on the list) as an example. Notice that the Class column for this check is blank. 

When I open this check, I get this result. Notice that there's a class assigned to the line item of this transaction. 

What you need to do is assign a class at the top of the check. I'll use Remodel in this example: 

I went back to the Transaction Detail by Account report and got this result:

You can also view this article for more information about sorting reports by class: Filter, sort or total reports by Class. 

I also suggest you open this article: Understand reports. It has a detailed description of Source and Targets, and how QBDT uses them to generate reports. 

Don't hesitate to leave a comment below if you have other questions about classes in reports. I'll be around to help you out. Enjoy the rest of the day!