Items Control Topic Related

Make sure that IsSelected is a property within the MetmastAssetAdapter class.

Your MetmastAssetAdapter class should implement INotifyPropertyChanged so that changes to the IsSelected property notify the UI.

public class MetmastAssetAdapter : INotifyPropertyChanged
{
    private bool _isSelected;
    public bool IsSelected
    {
        get { return _isSelected; }
        set
        {
            if (_isSelected != value)
            {
                _isSelected = value;
                OnPropertyChanged(nameof(IsSelected));
            }
        }
    }

    public string Name { get; set; }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Instead of using a simple List, use an ObservableCollection in your ViewModel:

public ObservableCollection MetMasts { get; set; }

Then, populate it in the ViewModel:

MetMasts = new ObservableCollection
{
    new MetmastAssetAdapter { Name = "Item 1", IsSelected = false },
    new MetmastAssetAdapter { Name = "Item 2", IsSelected = false },
    new MetmastAssetAdapter { Name = "Item 3", IsSelected = false }
};