Admob-free makes ion-header non-functional in IOS

Hello
I have used cordova-plugin-admob-free plugin for AdMob. The header buttons like back button are not functioning in where Admob present in IOS. Where there is no Admob all the header buttons working properly.
How to make the header buttons functional where Admob present in IOS?

Here is my ionic info output

Ionic:

ionic (Ionic CLI) : 4.10.3 (/usr/local/lib/node_modules/ionic)
Ionic Framework : ionic-angular 3.9.2
@ionic/app-scripts : 3.2.2

Cordova:

cordova (Cordova CLI) : 8.1.2 (cordova-lib@8.1.1)
Cordova Platforms : android 7.1.4, ios 4.5.5
Cordova Plugins : cordova-plugin-ionic-keyboard 2.1.3, cordova-plugin-ionic-webview 2.3.1, (and 23 other plugins)

System:

ios-sim : 6.1.3
NodeJS : v10.15.1 (/usr/local/bin/node)
npm : 6.4.1
OS : macOS High Sierra
Xcode : Xcode 10.1 Build version 10B61