SwiftUI ForEach View does not update when underlying @StateObject dictionary is updated

Here are the pieces. I'm trying to have the UI button update the data in Data and have SwiftUI automatically update another sibling View (that is based on the Data model). The Data model dict is updated, but the Cell view in ForEach does not update.

// main view (ContentView)

import SwiftUI

struct ContentView: View {

    @StateObject private var data = Data()
    @State private var cells: [Int: [Cell]] = [:]

    var body: some View {
        VStack {
            Text("Debug me")

            if let items = cells[0] {
                ForEach(items) { item in
                    item
                }
            }
        }
        .onAppear {
            setup()
        }
    }

    private func setup() {
        var newData: [Cell] = []
        newData.append(Cell(key: "A", data: data, text: "1"))
        newData.append(Cell(key: "B", data: data, text: "2"))
        newData.append(Cell(key: "C", data: data, text: "3"))
        cells[0] = newData
    }
}

// child view (Cell)

import SwiftUI

struct Cell: View, Hashable, Identifiable {
    @State private var key = ""
    @ObservedObject private var data: Data

    @State var text: String

    init(key: String, data: Data, text: String) {
        self.key = key
        self.data = data
        self.text = text
    }

    // Identifiable
    var id: String {
        return "\(key)\(text)"
    }

    // Hashable
    func hash(into hasher: inout Hasher) {
        hasher.combine(key)
        hasher.combine(text)
    }

    // Equatable
    static func ==(lhs: Cell, rhs: Cell) -> Bool {
        return lhs.key == rhs.key && lhs.text == rhs.text
    }

    var body: some View {
        HStack {
            Text(key)
            Text(" / ")
            Text(text)
            Button(action: confirm) {
                Label("", systemImage: "checkmark")
            }
        }
    }

    private func confirm() {
        // contrived example
        // this does not work
        data.updateValue(key: "C", value: "updated123")
    }

}

// data class (Data)

import SwiftUI

class Data: ObservableObject {

    @Published var data: [String:String]

    init() {
        data = [:]
    }

    func updateValue(key: String, value: String) {
        data[key] = value
        objectWillChange.send()
    }

}

As I wrote in the comment above the Cell view doesn't make use of the observed object so that it and the other properties are completely independent of each other.

Below is my version of Cell where I have made text into a computed property since this is actually what it represent, the value you get from the observed objects published property given the key value.

struct Cell: View, Hashable, Identifiable {
    @State private var key = ""
    @ObservedObject private var data: DataModel

    var text: String { data.data[key] ?? "" }

    init(key: String, data: DataModel, text: String) {
        self.key = key
        data.data[key] = text
        self.data = data
    }

    var body: some View {
        HStack {
            Text(key)
            Text(" / ")
            Text(text)
            Button(action: { confirm(key) }) {
                Label("", systemImage: "checkmark")
            }
        }
    }

    private func confirm(_ key: String) {
        data.updateValue(key: key, value: "\(Int.random(in: 1...100))")
    }

    var id: String { "\(key)" }
    func hash(into hasher: inout Hasher) { hasher.combine(key) }
    static func ==(lhs: Cell, rhs: Cell) -> Bool { lhs.key == rhs.key }
}

Note that I made key into a constant since it is the unique identifier for each cell and that I also removed text when conforming to the protocols because key is unique. And I renamed Data to DataModel