There are 3 factors due to which many times the student name might not show in the attendance list. Following are they -
1. The student status is not set as enrolled. (You can check this on the edit student details page)
2. The student status in that batch is not set as enrolled
3. The student cohort start date has to be either blank or set as the date before the attendance date
4. Registration date is mandatory and it has to be before the attendance date
