Swiftui Button to behave like a checkbox doesn't preview but works

Here's the code for the Checkbox I created. It works great but in the Xcode preview canvas it doesn't work. As in, in the preview when you click it, it doesn't change. When I use the checkbox in my app and run it in the simulator it works great. Any ideas why this is?

//
//  CheckboxToggle.swift
//  
//
//

import SwiftUI

enum CheckboxShape : String {
    case circle = "circle"
    case square = "square"
}

struct Checkbox: View {
    
    @Binding var isChecked:Bool
    var style:CheckboxShape
    @State var action:(Bool)->() = {_ in }
    
    var body: some View {
        Button {
            isChecked.toggle()
            action(isChecked)
        } label: {
            let shape = style.rawValue
            Image(systemName: isChecked ? "checkmark.\(shape).fill" : "\(shape)")
              .resizable()
              .frame(width: 24, height: 24)
              .foregroundColor(isChecked ? .green : .gray)
              .font(.system(size: 20, weight: .regular, design: .default))

        }
        .buttonStyle(PlainButtonStyle())
    }
}

struct Checkbox_Previews: PreviewProvider {
    @State static var isChecked:Bool = false
    // Not sure why this preview doens't work but the view works in other views fine.
    static var previews: some View {
        HStack {
            Checkbox(isChecked: $isChecked, style: .circle)
        }
    }
}

SwiftUI previews don't work this way.

To make Checkbox interactive declare isChecked as @State

@State var isChecked = false

and replace the PreviewProvider with

struct Checkbox_Previews: PreviewProvider {
    static var previews: some View {
        Checkbox(style: .circle)
    }
}

And if you want to see both states (and also the square appearance) and keep the @Binding add more Checkbox views and specify constants

struct Checkbox_Previews: PreviewProvider {
    static var previews: some View {
        HStack {
            Checkbox(isChecked: .constant(true), style: .circle)
            Checkbox(isChecked: .constant(false), style: .circle)
            Checkbox(isChecked: .constant(true), style: .square)
            Checkbox(isChecked: .constant(false), style: .square)
        }
    }
}

But this preview is not interactive.