Segment Facebook App Events not working on Android

Please provide the following:

  1. SDK Version: 39.0.0
  2. Platforms(Android/iOS/web/all): Android

I’ve connected expo-segment up to transfer data into Facebook App Events and after a lot of struggling it seems to work. Unfortunately I’m only getting iOS data coming through. No android events have appeared despite plenty of android users.
I’ve created two write keys, one for ios and one for android and use these in the initialisation.

Segment.initialize({
        androidWriteKey: config.SEGMENT_CLIENT_KEY_ANDROID,
        iosWriteKey: config.SEGMENT_CLIENT_KEY_IOS,
    });

Does anyone know why this is happening?