The schedule for the previous year is removed from the site after school sites are rolled during summer. However, the schedule for the new school year is not displayed for students, parents, and teachers.
Schedule in School Loop is only displayed for the current term - it starts on the first day of the school year. Hence, no classes are visible before that.
Teachers can ask a School Admin to make the new schedule visible for them before start of the school year. Students will need to wait for the start of the school year to review the schedule in School Loop.