I'll make sure you'll get the data you need when filtering the Profit & Loss by Class report in QuickBooks Desktop (QBDT), @lmor.

Based on your description above, you may have a minor data issue with your company file that's why there's no drop-down while filtering the Profit & Loss by Class report. To fix this, you can utilize the built-in Rebuild Data tool. Here's how:

1. Go to the File menu.
2. Choose Utilities and select Rebuild Data.
3. On the QuickBooks Information window, select OK. Follow the onscreen steps to save a backup.
4. Let the tool repair your file. It may take some time. QuickBooks may seem stuck, but as long as you can move your mouse, the tool is working.
5. When the tool finishes, select OK.
6. Go to the File menu.
7. Choose Utilities and select Verify Data.
8. Let the tool check your file for data issues.

After the steps above, go ahead and pull up the Profit & Loss by Class report again. Then, filter the data you need. Please see the screenshot below for your reference.

Once you're done and the issue persists, I'd recommend checking out this article to know other recommend solutions: Fix data damage on your QuickBooks Desktop company file.

Also, when pulling up reports, you can customize them to focus on the details that matter the most to you. Then you can memorize them to save its current customization settings for future use. You can check out this article for the complete details: Create, access, and modify memorized reports.

Let me know if you have other concerns about customizing reports and managing class transactions in QBDT. I'm just around to help. Take care, and wishing you continued success.