Emails do not respect edited enrol dates

[mfw-tn]

We use Reengagement frequently to send scheduled emails to students relative to their enrolment date. For example, all students get emails at 4 days past enrolment, 9 days past, etc. The emails are sent to all students with no other restrictions.

We enroll students by importing them into Moodle and specifying the course enrolment date and time. We have found that if we make a change to the enrolment date/time for a student after their original enrolment, this does not affect when the emails are sent. For example, if we added a student with an enrolment date of Jun 1 at 12pm, and then changed that date to June 3 at 12 pm, they would receive the "4 days past enrolment" email on Jun 5, which is 4 days past their original enrolment date.

We have also found this behavior to be true if we remove a student from a course entirely and then re-enrol them with a different enrolment date. Their original enrolment date from their first enrolment continues to determine when they receive their emails, regardless of what their updated enrolment date is.

[danmarsden]

this partially relates to #52 - if you have internal development capabilities, pull requests are always welcome, otherwise feel free to reach out privately if you would like to fund improvements to the plugin!