Data not showing in Firestore Emulator UI for Flutter App

I'm using firestore at the local environment using Emulator Suite and am able to successfully read and write data on my Flutter app. But in a scenario where I use

          .collection('messages')
          .doc(message.from)
          .collection(message.to)
          .add({
        'from': message.from,
        'to': message.to,
        'text': message.text,
        'time': message.time,
        'isSent': message.isSent,
        'isRead': message.isRead
      });

data is stored and retrieved successfully. But the problem is I'm not able to see it in Emulator UI. On the app, it's working fine, but why is it not showing up in the interface?

Even other data that I store normally using collection('data').set({...}) it shows up in UI, but not it's same in the above case.