I have a simple model with a unique field. @Model class M { @Attribute(.unique) var value: String var date: Date var answer: Int init(value: String, date: Date = .now, answer: Int = 0) { self.value = value self.date = date self.answer = answer } } I am creating new objects with let x = M(value: "x") modelContext.insert(x) The value field has a unique constraint, and I am observing these differences in iOS 18 beta (Xcode 16.0 beta) from iOS 17.5 (Xcode 15.4): Multiple objects with the same value field appear in the list. If explicit modelContext.save() is called, list is not updated with latest values. Is this something I need to adjust to, or beta issues? Full source code: https://github.com/paiv/swiftdata-insert-unique-1