Unity test ad

Hello everyone! I have completed my first game in Unity and I have implemented the test ads, which are working fine; however, for some reason now when I am testing it on my phone (which I had previously tested with no issues), when I click ‘Retry’, it will show the test ad and after the test ad, the scene will load, but if time runs out again and I click on ‘Retry’, nothing happens (the test ad will not show nor will the scene load). I am still new to coding, so any and all help is appreciated!

The codes for the Ads Initializer and Interstitial ad are below (I put 2 asterisks in front of the beginning of the Interstitial ad, so it doesn’t look like it’s running together):

public class AdsInitializer : MonoBehaviour, IUnityAdsInitializationListener
{
    [SerializeField] string _androidGameId;
    [SerializeField] string _iOSGameId;
    [SerializeField] bool _testMode = true;
    private string _gameId;


    [SerializeField] Interstitial interstitial;
      
    void Awake()
    {
        InitializeAds();
    }

    public void InitializeAds()
    {
#if UNITY_IOS
            _gameId = _iOSGameId;
#elif UNITY_ANDROID
            _gameId = _androidGameId;
#elif UNITY_EDITOR
            _gameId = _androidGameId; //Only for testing the functionality in the Editor
#endif
        if (!Advertisement.isInitialized && Advertisement.isSupported)
        {
            Advertisement.Initialize(_gameId, _testMode, this);
        }
    }


    public void OnInitializationComplete()
    {
        Debug.Log("Unity Ads initialization complete.");
        interstitial.LoadAd();
    }

    public void OnInitializationFailed(UnityAdsInitializationError error, string message)
    {
        Debug.Log($"Unity Ads Initialization Failed: {error.ToString()} - {message}");
    }
}
public class Interstitial : MonoBehaviour, IUnityAdsLoadListener, IUnityAdsShowListener
{
    [SerializeField] string _androidAdUnitId = "Interstitial_Android";
    [SerializeField] string _iOsAdUnitId = "Interstitial_iOS";
    string _adUnitId;

    void Awake()
    {
        // Get the Ad Unit ID for the current platform:
        _adUnitId = (Application.platform == RuntimePlatform.IPhonePlayer)
            ? _iOsAdUnitId
            : _androidAdUnitId;
    }

    // Load content to the Ad Unit:
    public void LoadAd()
    {
        // IMPORTANT! Only load content AFTER initialization (in this example, initialization is handled in a different script).
        Debug.Log("Loading Ad: " + _adUnitId);
        Advertisement.Load(_adUnitId, this);
    }

    // Show the loaded content in the Ad Unit:
    public void ShowAd()
    {
        // Note that if the ad content wasn't previously loaded, this method will fail
        Debug.Log("Showing Ad: " + _adUnitId);
        Advertisement.Show(_adUnitId, this);
    }

    // Implement Load Listener and Show Listener interface methods: 
    public void OnUnityAdsAdLoaded(string adUnitId)
    {
        // Optionally execute code if the Ad Unit successfully loads content.
    }

    public void OnUnityAdsFailedToLoad(string _adUnitId, UnityAdsLoadError error, string message)
    {
        Debug.Log($"Error loading Ad Unit: {_adUnitId} - {error.ToString()} - {message}");
        // Optionally execute code if the Ad Unit fails to load, such as attempting to try again.
    }

    public void OnUnityAdsShowFailure(string _adUnitId, UnityAdsShowError error, string message)
    {
        Debug.Log($"Error showing Ad Unit {_adUnitId}: {error.ToString()} - {message}");
        // Optionally execute code if the Ad Unit fails to show, such as loading another ad.
    }

    public void OnUnityAdsShowStart(string _adUnitId) { }
    public void OnUnityAdsShowClick(string _adUnitId) { }
    public void OnUnityAdsShowComplete(string _adUnitId, UnityAdsShowCompletionState showCompletionState)
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
    }
}