SwiftUI not updating Core Data after change?

I've got a core data model, with a name, which I've cleverly called cdName. My view has:

    @Environment(\.managedObjectContext) private var viewContext
    @FetchRequest(sortDescriptors: [
        SortDescriptor(\Item.cdName),
    ])
    private var items: FetchedResults<Item>

and then, later

                ForEach(self.items, id: \.self) { item in
                    NavigationLink {
                        ItemView(item: item)
                            .environment(\.managedObjectContext, self.viewContext)
                    } label: {
                        LabelWithMenuView(label: item.cdName ?? "<no name>") { ptr in
                            if let newName = ptr {
                                let oldName = item.cdName!
                                item.cdName = newName
                                do {
                                    try self.viewContext.save()
                                } catch {
                                    print("Could not save rename of \(oldName) to \(newName)")
                                }
                        }

(LabelWithMenuView is a view that has an on-hover button which brings up a rename sheet and passes the new name off to the completion handler.)

When I do this (macOS)... it does change the name in Core Data, but it doesn't update the view. If I quit&restart my app, it shows up with the new name.

What am I doing wrong, please?