Quiz Summary: Multiple Attempts

Community Champion

I had instructor give a quiz.  There are a total of 21 students in the class, and all 21 took a quiz last week.  When I click on Quiz Statistics, the Quiz Summary only shows 15 respondents and their coordinating responses.  The instructor allowed two attempts.  The remaining six used the two attempts, and their responses are not showing up on the Quiz Summary.  Is this the norm?  I thought the Quiz Summary reflected the highest scores when multiple attempts are given?