I've had a persistent but hard to reliably reproduce issue when using SwiftData with SwiftUI. Sometimes, when some properties of a SwiftData model object are used in the UI (like the title of a note in a list of notes) and something in the model is modified, the UI stops responding. The modification in the model could be a completely different object and of a different type and could be as simple as toggling a Bool, it could be performed on the main thread from inside a Button's action using the ModelContext from the environment or on a separate thread using a ModelActor. The issue even appears and disappears between builds of the same code. As an example, this is the kind of code that leads to this issue, though I haven't been able to make a minimal reproduction because of how inconsistently it appears: @ModelActor struct NoteModifier { func append() { guard let notes = try? modelContext.fetch(FetchDescriptor<Note>()) else { return } notes.randomElement()!.title.append("ABC") try? modelContext.save() } } struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var notes: [Note] var body: some View { VStack { List { ForEach(notes) { note in VStack { Text(note.title) Text(note.contents) } } } Button { Task { await NoteModifier(modelContainer: modelContext.container).append() } } label: { Text("Bug") } } } } When it happens and I try pausing execution, it's locked inside kevent_id in the getter for one of the properties of my model object like this: In Instruments: