I see that this has been asked and answered in Mooodle forums for over 4 years, but it is still an issue. I set up a lesson and in the settings selected: Grade>Practice lesson>yes.

I tested it from a student id and completed the lesson (which consists of 10 questions, no branches and the last question leads to "end of lesson"). I switched back to Admin to view the results only to get the message: "No attempts have been made on this lesson." I redid the lesson, same results. I redid the lesson 4 times.

After searching the forums and finding that other people have had the same problem, I saw that turning off the practice lesson option fixed it for other people. I tried it and TADA it fixed the problem.

The Practice lesson option shouldn't break reporting of actual attempts. If 4 attempts at the lesson are all considered "practice" then the option should be changed to "ONLY allow practice attempts".