Enrollments are synched to an enrollment id, not to a user id in moodle

One of our moodle customers has a course where they manually enroll accounts, and then the accounts complete some work and then the enrollment removed and the account is removed.  They have their resones for doing this.  A few times - people have called us saying they cannot access the course anymore.

I was testing a theory that if: 


We left the account in the system, they could remove the enrollment from the course and in a case where the student still needed access to the course - we could re-enroll the same account into the course and the work that the account had completed would re- synch.

In other words I asserted that the work saved in the course was synched by the user id.  I was incorrect.

The association of the progress of an account in a course must be accomplished via an enrollment ID, not the user ID.

This was my scientific process applied to prove or dis-prove my theory.

1. manually enrolled an account in the course
2. completed some of the course (verified the grades in the User report in the course)
3. removed the manual enrollment.
4. enrolled the same account back into the course
5. viewed the grades in the User report for the account in the course, and saw nothing.

Before removing enrollment of the account

After removing account and re-enrolling the same account

The end.