If I close and archive a group or individual course, what happens to the lessons that were put in status to be retrieved?

A course, collective or individual, that is closed and then archived (or even just closed), causes the final cancellation of the lessons put in status to be retrieved with the consequent impossibility of rescheduling them. In fact, the system, only asks whether or not to leave open, lessons for which attendance has not been entered, while it will cancel all future lessons and those precisely put in status to be retrieved.

Therefore, in case you need to make up in the future (e.g., in the next educational year) lessons previously put in a status to be made up, it is recommended to leave those courses temporarily open until those lessons are rescheduled.
Those classes will always be grouped together in the section Didactics → Lessons to be Retrieved, or from the list of courses it will then be possible to filter by specific instructional year to view courses from that year that have not yet been archived and therefore have lessons yet to be rescheduled.