Wait in Coroutine doesn't work

I tried to implement a countdown timer after the user has hit the resume game option. The option is just a text with event trigger set to OnMouseDown attached to it. The text also has a pause script which reads:

 public void  pauseGame() {
         if (!pause) {
             pauseNoJump = true;
             Time.timeScale = 0f;
             pause = true;
             pauseText.text = "►";
         }
         else
             {
             pauseText.text = "||";
             StartCoroutine(StartingUp());
 
             }
         
     }

 IEnumerator StartingUp() {
     pauseText.text = "3";
     yield return new WaitForSeconds(1);
     pauseText.text = "2";
     yield return new  WaitForSeconds(1);
     pauseText.text = "1";
     yield return new  WaitForSeconds(1);
     pauseNoJump = true;
     pause = false;
     Time.timeScale = 1f;
     pauseText.text = "||";
 }

but it doesn't go pass the first WaitForSeconds. My guess is so how something gets destroyed in a even trigger and the coroutine hangs up. The text does changed to 3 meaning the coroutine started. Any ideas what could've been done? Thank you