Fade transition won't work in build.

Hi I am having problems with my fading transition when I move to a different scene. The code actually works in the Unity Editor, but when I build and run it, the fader stops working and I just blink to the next scene without the transition. What did I do wrong?

Here is the code:

  public class LoadLevel : MonoBehaviour
     {
         public string words;
         public Animator transition;
         public bool loadsave;
     
         public void LoadNextNevel()
         {
             
             StartCoroutine(Loadlevel());
     
         }
         public void LoadSaveLevel()
         {
     
             StartCoroutine(Loadsave());
     
         }
     
         IEnumerator Loadlevel()
         {
            
             transition.SetTrigger("Start");
             yield return new WaitForSeconds(1);
             SceneManager.LoadScene(words);
         }
         IEnumerator Loadsave()
         {
             
             transition.SetTrigger("Start");
             yield return new WaitForSeconds(1);
             SceneManager.LoadScene("FirstLevelEdit");
             
         }
     }