Swift array.append() not working as expected

Question

I'm new to Swift and can't seem to get this append method working, any help would be appreciated!

Here are my models and view:

import SwiftUI

struct ContentView: View {
    @Binding var gameInformation: GameInformation
    
    var body: some View {
        VStack(alignment: .center) {
            Button("Append") {
                let index = gameInformation.sets.firstIndex(of: gameInformation.sets.last!)
                gameInformation.sets[index!].legs.append(Leg())
                print(gameInformation.sets[index!].legs)
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView(gameInformation: .constant(GameInformation()))
    }
}

struct GameInformation: Identifiable, Codable {
    var id = UUID()
    
    var sets: [Set] = [Set()]
    
    enum CodingKeys: String, CodingKey {
         case id, sets
     }
}

struct Set: Codable, Equatable, Identifiable {
    static func == (lhs: Set, rhs: Set) -> Bool {
        return lhs.id == rhs.id
    }
    
    var id: String = UUID().uuidString
    var legs: [Leg] = []
}

struct Leg: Codable, Identifiable {
    var id: String = UUID().uuidString

    var playerOneScores: [Int] = []
    var playerTwoScores: [Int] = []
}

As you can see I have a parent GameInformation model, this has sets which is an array of Set, and then Set has legs which is an array of Leg, the button in the content view simply adds a new Leg but when the value of gameInformation.sets[index!].legs is printed, there's only one entry which is the initialised value.

Thanks again for any help.