Unity Ads IUnityAdsListener.OnUnityAdsDidFinish NotImplementedException. Fixes?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Advertisements;
 using UnityEngine.SceneManagement;
 
 public class AdManager : MonoBehaviour, IUnityAdsListener
 {
     string AppStore_ID = "3862326";
     bool testMode = true;
     string myPlacementId = "rewardedVideo";
     bool runningPauseAd;
     bool loadSceneOnDone;
     string sceneToLoad;
     public bool premiumNoAds;
 
     // Start is called before the first frame update
     void Start()
     {
         Advertisement.Initialize(AppStore_ID, testMode);
         Advertisement.AddListener(this);
     }
 
     public void DisplayInterstitialAd()
     {
         if (Application.internetReachability == NetworkReachability.NotReachable)
         {
             //Give internet connectivity feedback here
 
             return;
         }
         Advertisement.Show();
     }
 
     public void DisplayVideoAdAndPauseGame()
     {
         if (Application.internetReachability == NetworkReachability.NotReachable)
         {
             //Give internet connectivity feedback here
 
             return;
         }
         print("Running Video Ad...");
         Time.timeScale = 0;
         runningPauseAd = true;
         Advertisement.Show(myPlacementId);
     }
 
     public void DisplayVideoAdAndPauseGameAndLoadScene(string scene)
     {
         if (Application.internetReachability == NetworkReachability.NotReachable)
         {
             //Give internet connectivity feedback here
 
             return;
         }
         print("Running Video Ad...");
         Time.timeScale = 0;
         runningPauseAd = true;
         sceneToLoad = scene;
         Advertisement.Show(myPlacementId);
         
     }
 
     public void DisplayVideoAd()
     {
         if (Application.internetReachability == NetworkReachability.NotReachable)
         {
             //Give internet connectivity feedback here
 
             return;
         }
         print("Running Video Ad...");
         Advertisement.Show(myPlacementId);
     }
 
     // Implement IUnityAdsListener interface methods:
     public void OnUnityAdsDidFinish(string placementId, ShowResult showResult)
     {
         // Define conditional logic for each ad completion status:
         if (showResult == ShowResult.Finished)
         {
             // Reward the user for watching the ad to completion.
             print("Ad watched to completion");
             OnAdWatched();
         }
         else if (showResult == ShowResult.Skipped)
         {
             // Do not reward the user for skipping the ad.
             print("Ad skipped");
             OnAdSkipped();
         }
         else if (showResult == ShowResult.Failed)
         {
             Debug.LogWarning("The ad did not finish due to an error.");
         }
         throw new System.NotImplementedException();
     }
 
     private void OnAdWatched()
     {
         if (runningPauseAd)
         {
             Time.timeScale = 1;
             runningPauseAd = false;
         }
         if (loadSceneOnDone)
         {
             SceneManager.LoadScene(sceneToLoad);
             loadSceneOnDone = false;
         }
     }
     private void OnAdSkipped()
     {
         if (runningPauseAd)
         {
             Time.timeScale = 1;
         }
         if (loadSceneOnDone)
         {
             SceneManager.LoadScene(sceneToLoad);
             
         }
     }
 
     void IUnityAdsListener.OnUnityAdsReady(string placementId)
     {
         // If the ready Placement is rewarded, show the ad:
         if (placementId == myPlacementId)
         {
             
         }
     }
 
     void IUnityAdsListener.OnUnityAdsDidError(string message)
     {
         // Log the error.
     }
 
     void IUnityAdsListener.OnUnityAdsDidStart(string placementId)
     {
         // Optional actions to take when the end-users triggers an ad.
     }
     void OnDestroy()
     {
         Advertisement.RemoveListener(this);
     }
 }
 

Every time OnUnityAdsDidFinish() is called, a NotImplementedException is thrown, and the user is not rewarded for the ad. I am using the Advertisement Package (v3.4.2) through the Package Manager. Any fixes?