Instructors are not required to open/make courses visible to students until the first day of class. Some instructors do open their courses before the start of classes, but many choose to wait. As long as your courses appear under Registered Classes in ULink there is no need to worry.
Added or Dropped a class in the last 24 hours?
Students are added and removed automatically, based on roster information acquired daily from the Banner "snapshot". Since the "snapshot" is only updated once a day, there can be up to 24 hours delay processing drops and adds.
Missing Course in the middle of the semester?
During the semester, the Registrar's Office will purge classes for students are are listed as non-pay (those who have accounts in arrears) . Students are normally notified by University email that their classes will be purged.
See the Registrar's Office Important Dates & Deadlines page for purge dates for the current semester.