Log in to Blackboard Learn as an administrator (The issue can be reproduce as an Instructor in an existing Original course)

Go to System Administrator page > Courses > Courses > Create Course > New

Make sure that the course is set to Original view (only In case you have logged in to an Ultra environment)

Enable Quick Enroll in the course

Go to Course Menu > Control Panel > Users and Groups > Users

Enroll two users and assign them the Student role

Go to Course Menu > Control Panel > Users and Groups > Groups

Create two groups and add the users to the groups (One student per group)

Go to Course Menu > Content Area (Any content area in the course)

Hover over Assessments, then, select Assignment

Create a Group Assignment and assign it to one the groups created in step # 8

Go to Course Menu > Content Area

Locate the Assignment created previously

Click on the "Chevron" button (Contextual menu) and select Adaptive Release . Note that the Username field is greyed out and the Course Groups field is not editable; the following message is shown in the membership section: "The membership for this item is controlled by the groups set in the Item Properties."

Navigate back to the Course Content area, repeat the previous step but selecting Adaptive Release: Advanced

Note the fields Username and Course Groups are enabled, therefore, users and groups can be added.