Group Activity page does not show users joining or leaving the group

Summary

The "Activity" page for a group does not show items for a user joining or leaving the group. In a project's Activity page users joining or leaving the project are displayed, and users joining/leaving a project inside a group are also shown in the group's Activity page, but not users joining/leaving the group

Steps to reproduce

Create a group. Add a user to the Members list. Go to Activity.