Currently any messages sent using messaging().send(...) have a TTL of 0. If the device is offline they won't be sent when it reconnects. Adding a TTL handles this for us but it's currently not set.

Locally on Android I've added this myself below this line: https://github.com/fullstackreact/react-native-firestack/blob/master/android/src/main/java/io/fullstack/firestack/FirestackCloudMessaging.java#L165

remoteMessage.setTtl(300);

This should be configurable/have a default.