Waitlisted user not getting enrolled

Summary:

Waitlisted user not getting enrolled when any user is withdrawn or even completed the course

Content (required):

We have created a course where we have defined the capacity as 2 ,

Scenario 1: When we have enrolled 2 users and both users have completed the course and the 3rd person enroll to it the it shows waitlist position 1. As the above two users has already completed the course so 3rd user should be enrolled automatically but it is not happening.

scenario 2: When we have enrolled 2 users and one of the users have withdrawn the course and the 3rd person enroll to it the it shows waitlist position 1. As the above 1st user has already withdrawn the course so 3rd user should be enrolled automatically but it is not happening.