Problem with Question 1 (updated, question withdrawn)

EDIT: My bad. I misunderstood the UI response. I interpreted the ‘greyed out’ TRY AGAIN button as an ERROR, not as ‘Answer accepted’.

I withdraw this concern, but will leave it here in case anyone else encounters the same issue.

The question is

…determine the range of values for the usertype field. Which of the following are values found in this collection for the field usertype?

I find only certain values for "usertype" but my answer is rejected. I am struggling to find more values, and I suspect there is an error with the exam.

I troubleshot the problem this way:

db.trips.find({}).count() is y

When I add up the count of queries for each of the "usertype" values I found, the counts add up to the total.
db.trips.find(<value 1 for usertype>).count() is x1
db.trips.find(<value 2 for usertype>).count() is x2
… and so on

and x1 + x2 + ... = y

These counts all sum to the total, which would not be the case if I were missing a value. Could a proctor invalidate this please? Or what am I missing?