Google Mobile Ads not playing

So i'm getting ready to release my app to the play store and I got everything setup Google Play Services and Mobile Ads. I follow the instructions perfectly and I get NO errors. I only have one ad and its set to run every time the player completes 3 rounds in the game, however, nothing appears when I try testing it.

Something people are probably gonna ask
1. Yes it in an alpha track and my gmail is on the list of testers.
2. Yes my Ad Unit id is correct
3. Yes I am loading the ad before showing it.
4. Yes my build target is android.

if I've missed something important let me know, I know the code is a mess but i'll refactor it when the ads are working ;p //Called in start void AdServicesSetup() { #if UNITY_ANDROID string appId = "App id"; #endif MobileAds.Initialize(appId); mainAd = new InterstitialAd("Ad Id"); AdRequest request = new AdRequest.Builder().Build(); mainAd.LoadAd(request); } //Called when the round ends public void GameEnd() { _gameOverPanel.SetActive(true); _rounds++; Social.ReportScore(_spawner.spawnedCubes, GPGSIds.leaderboard_most_cubes_stacked, success => {}); if(_rounds == 3) { if(mainAd.IsLoaded()) { mainAd.Show(); _rounds = 0; } else { Debug.Log("Ad is not loaded"); } } _isRunning = false; _spawner.StopSpawning(); _platform.enabled = false; }