Admob interstitial doesn't show on Android

I have a problem. My admob interstitial doesn’t show on any Android device when set istesting = false but it works fine when istesting = true and works fine on iOS.

const AdmobConfig: AdMobFreeInterstitialConfig = {
      id: 'ca-app-pub-8966855633814872/196503XXXX',
      autoShow: true,
      isTesting: false


    this.admobFree.interstitial.prepare().then(() => {;
    }).catch(e => console.log(e)); 


Could anyone help me?

Wait for 1-2 days, and banner ads is working?