Tasks are grouped into Milestones in a Course.You can assign a task to a milestone only after it has been created in the Milestones tab in the Admin Panel.Tasks which are not assigned to a milestone are displayed as Uncategorized to learners.
You can assign a milestone to a task either while creating a task or after a task is created. You can see the milestone a task is assigned to in the Tasks page.
While creating a task
After a task is created
Here is how you can assign a milestone to multiple tasks at once!