Cannot display ads with Admob Free (Android)

Ionic version:
[ ] 2.x
[X] 3.x
[ ] 4.x

I’m submitting a …
[X] bug report
[ ] feature request

Current behavior:
I can’t display banner ads and interstitial are always test ads. Sometimes it just works but after another build it stops working

Expected behavior:
We should be able to display ads with our IDs

Steps to reproduce:
App in pro: https://play.google.com/store/apps/details?id=drodriguez.apps.Words&hl=en
The banner is not being display at top and before playing interstitial is displayed as test ad.

Related code:

import { Injectable } from '@angular/core';
import { AdMobFree, AdMobFreeBannerConfig } from '@ionic-native/admob-free';

@Injectable()
export class AdmobProvider {

  constructor(private adMobFree: AdMobFree) {
  }

  async showBanner() {
    try {
      const bannerConfig: AdMobFreeBannerConfig = {
        id: 'ca-app-pub-2945024608555072/7448431344',
        isTesting: false,
        autoShow: true,
        bannerAtTop: true
      };
      this.adMobFree.banner.config(bannerConfig);
      this.adMobFree.banner.prepare()
        .then(() => { })
        .catch(e => console.error(e));
    }
    catch (e) {
      console.error(e);
    }
  }

  async showInterstitial() {
    try {
      const bannerConfig: AdMobFreeBannerConfig = {
        id: 'ca-app-pub-2945024608555072/6152521340',
        isTesting: false
      };
      this.adMobFree.interstitial.config(bannerConfig);
      this.adMobFree.interstitial.prepare()
        .then(() => {
        })
        .catch(e => console.error(e));
    }
    catch (e) {
      console.error(e);
    }
  }

  async showVideo() {
    try {
      const bannerConfig: AdMobFreeBannerConfig = {
        id: 'ca-app-pub-2945024608555072/7816300482',
        isTesting: false
      };
      this.adMobFree.rewardVideo.config(bannerConfig);
      this.adMobFree.rewardVideo.prepare()
        .then(() => { })
        .catch(e => console.error(e));
    }
    catch (e) {
      console.error(e);
    }
  }
}

Other information:
Tried also with Admob Pro and getting same issue. Also created issue on Admob Free repo:
https://github.com/ratson/cordova-plugin-admob-free/issues/119.

Also in Ionic repo:

I haven’t tried on iOS.

Ionic info: (run ionic info from a terminal/cmd prompt and paste output below):

cli packages: (/usr/local/lib/node_modules)

    @ionic/cli-utils  : 1.19.1
    ionic (Ionic CLI) : 3.19.1

global packages:

    cordova (Cordova CLI) : 8.0.0

local packages:

    @ionic/app-scripts : 3.1.8
    Cordova Platforms  : android 6.4.0 ios 4.5.4
    Ionic Framework    : ionic-angular 3.9.2

System:

    Android SDK Tools : 26.1.1
    Node              : v8.9.0
    npm               : 5.6.0
    OS                : OS X El Capitan
    Xcode             : Xcode 8.2 Build version 8C38

Environment Variables:

    ANDROID_HOME : /Users/danielrodriguez/Library/Android/sdk/

Misc:

    backend : pro