I want to update one property of an object inside ObservableCollection

Hi , I am struggling with a problem, my ObservableCollection doest refresh after change in code behind.

  private ObservableCollection<NotificationModel> _notifications = new ObservableCollection<NotificationModel>();

        public ObservableCollection<NotificationModel> Notifications
        {
            get => _notifications;
            set
            {
                _notifications = value;
                RaisePropertyChanged(nameof(Notifications));
            }
        }

this is my list,

After click on some item I Want to update the color of it

 var notification =  _notifications.First(x => x.Id == itemInfo.Id);
                notification.NotificationColor = "#FFFFFF";

but it doesnt work