How to bind the 'Selected' property for a UIButton in MvvmCross - uibutton

Question

I have a weird thing. On the Simulator iOS 10.3. the following code works just fine.
set.Bind(Circle1).For("Selected").To(vm => vm.PincodeCircles[0].Activated);
On my iPad Pro 12.9 I get an error saying the following:
[0:] MvxBind:Warning: 2.68 Failed to create target binding for binding Selected for PincodeCircles[0].Activated
I've already tried the following:
set.Bind(Circle1).For(button => button.Selected).To(vm => vm.PincodeCircles[0].Activated);
and gives the same error:
[0:] MvxBind:Warning: 4.27 Failed to create target binding for binding Selected for PincodeCircles[0].Activated
Activated is defined as follows on the viewmodel:
public bool Activated
{
get { return this._activated; }
set { this.SetProperty(ref this._activated, value); }
}
The Cirle1 button is of type UICircleButton. Here's the class:
using CoreGraphics;
using Foundation;
using System;
using UIKit;
namespace NN.Plugin.Utils.iOS
{
public partial class UICircleButton : UIButton
{
public UICircleButton(IntPtr handle) : base(handle)
{
Layer.BorderColor = UIColor.Black.CGColor;
Layer.BorderWidth = 2;
}
public nfloat BorderWidth
{ get
{
return Layer.BorderWidth;
}
set
{
Layer.BorderWidth = value;
}
}
public CGColor BorderColor
{
get
{
return Layer.BorderColor;
}
set
{
Layer.BorderColor = value;
}
}
public nfloat PointSize
{
get => Font.PointSize;
set => Font = Font.WithSize(value);
}
public override CGRect ContentRectForBounds(CGRect rect)
{
var newRect = base.ContentRectForBounds(rect);
Layer.CornerRadius = newRect.Width / 2;
return newRect;
}
}
}