In Canvas Conferences, when a conference is created it is accessible only to those listed in the Members section.
When you create a Canvas Conference, Canvas automatically creates an associated "access control list" (ACL) of course members that access the conference and view its subsequent recordings.
By default, the ACL for a conference is all students enrolled in the course at the time you create the conference.
Before starting the conference, you can edit the ACL by unchecking "Invite All Course Members" and choose a subset of the current course members.
For example, in the above screenshot, John Doe and Jesus Federico in the Members list for the conference. Only those two users will be able to see the conference, join it, and view the subsequent recordings.
Once the conference is started, the ACL is fixed.
A problem occurs when a student is added to the course after a conference is created. In this case, the student will not be able to see any previous conferences, nor view their recordings, because they were not a member when the conference was created. They are not in the conference's ACL.
When a student is added to the course after a conference is created, they are not automatically added to the Members list.
In this case, the student will not be able to see any previous conferences, nor view their recordings, because they were not a member when the conference was created.
As long as the conference is in progress (not ended), you edit the conference and add more students to the Membership list.
Alternatively, you can use the shortcut "Sync Attendees" to have Canvas add all current course members to the access control list. This make it easy to quickly add members enrolled in the course after the conference was created.
If the conference is concluded, there is no ability to edit the membership list anymore.