Missing Push Icon with new android:targetSdkVersion

I’m trying to integrate push notifications into my ionic app with the ngCordova Push plugin (http://ngcordova.com/docs/plugins/pushNotifications/).

When I set my android:targetSdkVersion greater than 20, I’ll receive a blank push notification icon. With SdkVersion 20 it’s working properly.

Is there a fix for newer sdk versions or can i unproblematically use version 20? (performance, functionality)