I think I was running into a similar issue: EmbeddedRecordsMixin: Embedded hasMany is only visible after explicitly calling store.find()
I needed to wait for the hasMany relationship to be fulfilled before I was able to get the correct data. something like: client.get('offices').then((offices) => { console.log(offices.get('length'); }); should get you going. However, you might want to take this with a grain of salt, as I am not 100% sure if this really is exactly what is going on under the hood.