Delayed Button Sounds

Hello!

Yesterday I added button sounds to almost all buttons in the menu, but for some reason they are delayed on iPhone (0,2-0,5 seconds at most). What could be causing this? They are not delayed in the Unity editor. My audio source is the Main Camera.

 public class MenuButtons : MonoBehaviour
 {
         public GameObject loadScreen;
         public AudioClip buttonSound;
         public AudioSource audioSource;
     
         void Awake ()
         {
                 audioSource = audioSource.GetComponent<AudioSource> ();
         }
     
         public void MainMenu ()
         {
                 loadScreen.SetActive (true);
                 audioSource.PlayOneShot (buttonSound);
                 Application.LoadLevel ("Main Menu");
         }