New Quiz log shows "There are no session events to display yet."

[Mdb1]

I gave a quiz to 50 students, new style type and everything went  fine, or so I thought. 

When i checked one student's log (from the Moderate tab), instead of showing their quiz activity I get

There are no session events to display yet.

What could have gone wrong?  Any chance the student hacked in to enter answers?  Their score was rather low, and I doubt this student is a computer savy hacker but someone else could have done something for them or to their account.  or maybe they answered on their phone and the phone log is not supported,. 

[acb20739]

I've also just experienced this problem. One of my "tests" is actually a few related sequential New Quizzes; for the same student, for each quiz, I see this same error.

[acb20739]

Completed quizzes from this student in the same series show this error at the 'View Log' link; quizzes the student is actively working on ALSO show this error at the 'In Progress' link. This is additionally problematic since there's no way to tell how long the student has been working if this feature isn't functioning. (Classic quizzes showed time remaining on the moderate screen, but New Quizzes do not.)

[tpaulson]

This is happening for 2 of my students today also. first time I noticed it. I value the feature to monitor progress and whether students leave the quiz.

How are some students circumventing this ? I'm not sure it is purposeful, so does it only work with some browsers?