Push notifications to Android devices have stopped working since the beginning of this year for newly registered users on ACS while Notifications are being delivered to existing users on Android without any issue. Nothing changed in our code and app is in production mode.
We are using Titanium SDK 3.0.2 and MQTT. An upgrade for GCM based solution is planned and under testing and may take few weeks to release. So, looking for any quick fixes that can resolve the issue till our new release of app.