Dissapeared pupil

Hi,

I've created a group but one of the students doesn't appear in the list. Even though it says there are 26 students, I can only see 25. When I try to add her again, it says that the email is already taken but it cannot be because the student is not in the group. I cannot find where she can be and it's almost impossible the email is taken because we're using the school domain.

I'll agree your help,

Thank you.

Yolanda.