1. students do not appear to assign attendance. Any tips?
2.You can not export data because there are no students enrolled in the course." when you click on the report..
Are these separate problems?Please elaborate.
I have used the attendance module and i haven't found any problem as such. May be the session for attendance wouldn't have been set properly. Please login as student and check whether you are able to mark attendance. Then login with teacher and see if teacher is able to mark attendance. If these things are working fine then one can surely export attendances.
You can also have a look at it. https://docs.moodle.org/37/en/Attendance_activity.