I discovered these while working on another issue. There are multiple issues with the MNet remote enrolment method auth_plugin_mnet::update_enrolments()

• There is a typo in the table name "mnetervice_enrol_courses" (missing "s") so that the method has never worked since 2010 - and the exception was likely never noticed since it was threw on the remote MNet connection side.
• The list $local_courseid_array is populated with the "id" values from the "mnetservice_enrol_courses" but it is then compared with "remotecourseid" value in "mnetservice_enrol_enrolments" when deleting all extra enrolments. So it would actually delete other records than it should. This never happened because of the typo above.

As a result, the IdP has never had fully reliable and up-to-date information about remote courses the user is enrolled to on the remote MNet site.