When a user's role assignment is changed, the plugin currently checks whether the user is currently an owner of the team using in_array to determine whether the user has been demoted to a normal member (e.g. transitioned from a teacher to student).

However, the get_group_owners function returns an associative array in the form { "userid_1": user_representation_1, "userid_2": user_representation_2 }, so the check using in_array always returns false. Since the user IDs are the keys of the array, the function should instead use array_key_exists.