插入后CoreData关系未更新

I have a 1 to many relationship between 2 entities in my model. I fetch entity1 that is on the '1' side and access the relationships set. When I find that there are no items currently in the set I request information from my service, create/insert entities, set properties, set relationship back to entity1, and save the ManagedObjectContext. I have a 1 to many relationship between 2 entit