To tie the thread, I met with Sarah on a video conference and it was as Danny suspected. The instructor (who is not Sarah) has the problem set to 1 attempt. The one and only attempt was used up with a blank submission.
I showed Sarah how to use Instructor Tools to change the student's score, give additional attempts, and reopen the set for just that one student. And the instructor might consider whether they really want to limit to just one attempt.
Perhaps an empty submission should not count as an attempt. But in some rare situations, an empty string is the correct answer. So I don't know.
It is also evident that the message to the student that they only have one attempt or that they have used up all of their attempts did not come through clearly to the student. So perhaps we can do something about that for a future release.
I showed Sarah how to use Instructor Tools to change the student's score, give additional attempts, and reopen the set for just that one student. And the instructor might consider whether they really want to limit to just one attempt.
Perhaps an empty submission should not count as an attempt. But in some rare situations, an empty string is the correct answer. So I don't know.
It is also evident that the message to the student that they only have one attempt or that they have used up all of their attempts did not come through clearly to the student. So perhaps we can do something about that for a future release.