Issue in Diagnostic plugin

I have installed cordova.plugins.diagnostic in my mobile app. When i try to access camera, I’m trying to call requestCameraAuthorization, isCameraAuthorized methods, But In live APK file, it is not asking for permission to access camera and camera is not opening.

can some one please suggest what to do, I tried to install most of the versions of diagnostic but same error. when I run ionic serve -c i face issue like plugin_not_installed. Please help