This is due to the user having a Drop on their record in the daily feed supplied to myCourses. The Registrar's feed to myCourses is authoritative and will override any manual changes made to the Classlist of a course.
A Student may have a Drop or Withdrawal on their record. An Instructor or Teaching Assistant may have been assigned to the course previously and then been removed in the Registrar's records, which will create a Drop in the myCourses SIS feed.
To correct this, the Student enrollment or Instructor/TA assignment should be addressed properly in the Registrar's records by the academic department or the student's academic adviser. Any changes will be reflected on myCourses with the next daily feed.
Drop conflicts often occur with Teaching Assistants who enrolled in and then dropped the course they are to be a TA on. The Scheduling Officer for the college offering the course can add Teaching Assistant assignments to the courses in PeopleSoft/SIS. These assignments will come through the feed supplied to myCourses and override any drop on a student record for that course.
If an instructor is trying to manually enroll students on a Classlist to merge courses or sections together, the instructor should submit a Course Merge Request. This will merge the courses properly on the system and handle any drop conflicts appropriately.
As a last resort, a request can be submitted to Academic Technology Support to put a drop override in place. This requires the Registrar's feed to myCourses be intercepted every morning for the entire term to address the drop. All other methods stated above to properly address the issue should be explored before requesting a drop override.
For a student override, the request must be submitted in email to Academic Technology Support from the instructor of the course. For an Instructor or TA override, the request must be submitted in email to Academic Technology Support from the instructor of the course, or a Dean, Department Head, or Scheduling Officer of the academic department.