When using this.emberSync.find('post'), after fetching data from the server, the relationships are not pushed to the offline Store, only to the online Store: in ActiveModel serializer, extractArray pushes the relationships in the Store, while returning the primary Array. emberSync's find query uses the results returned by onlineSearch = this.onlineStore.find(type, query), which only returns the primary array.
To have the relationships pushed to the offlineStore, I had to override the ActiveModelSerializer:
When using this.emberSync.find('post'), after fetching data from the server, the relationships are not pushed to the offline Store, only to the online Store: in ActiveModel serializer, extractArray pushes the relationships in the Store, while returning the primary Array. emberSync's find query uses the results returned by onlineSearch = this.onlineStore.find(type, query), which only returns the primary array.
To have the relationships pushed to the offlineStore, I had to override the ActiveModelSerializer: