The reason the existing entities are not being returned is because they have not been indexed since you modified your entity class.The Objectify documentation states that:
Single property indexes are created/updated when you save an entity.
To get the existing existing entity instances to appear in your queries you will have to resave them, which will consequently force the Datastore to create their indexes.
You have to do the following for each existing entity:
- Retrieve (load) the existing entity from the Datastore
- Write (save) the existing entity back to the Datastore