IEnumerator Function

So I am currently using the IEnumerator function to pause a for loop, the for loop that contains a ball that should move to another game object. Currently from my print statements seems like the ball moves a little, but it's actually never reaching the object and I'm not sure why since I actually have never used IEnumerator so I'm not sure if this is apart of the issue.

 public IEnumerator CoUpdate(){ 
         float waitTime = 8;
     
         yield return new WaitForSeconds (waitTime);
 
             for (int i = 0; i <= 19; i++) {
                 //Finding Game Objects
                 numbers = GameObject.FindGameObjectsWithTag ("num");
                 ball = GameObject.FindGameObjectWithTag ("ball");
                 float step = speed * Time.deltaTime * 2;
 
                 //Picking the random cube
                 index = Random.Range (0, numbers.Length);
                 pickedNumber = numbers [index];
             
                 print ("number picked");
                 print (pickedNumber.name);
             
                 print ("numer postion");
                 print (pickedNumber.transform.position);
             
                 //Moving ball to cube
                 target = pickedNumber.transform;
                 ball.transform.position = Vector3.MoveTowards(transform.position, target.position, step);
             
                 //Checking balls position 
                 print ("ball Position");
                 print (ball.transform.position);
             
                 //Pause here
                 print ("PAUSE!");
                 yield return new WaitForSeconds (waitTime);
             
                 //Ball Returns to position
                 ball.transform.position = new Vector3 (0, 0, 0);
                 print ("ball reset");
                 print (ball.transform.position);
             }
 
     }