Use attached to reproduce:

- click on the second tab

- collapse the first group

- click the first tab

- click the second tab, both grids are visible

Workaround:

public RadForm1()
{
    InitializeComponent();
    new Telerik.WinControls.RadControlSpy.RadControlSpyForm().Show();

    layoutControlGroupItem3.PropertyChanged += LayoutControlGroupItem3_PropertyChanged;

}

private void LayoutControlGroupItem3_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    if (e.PropertyName == "IsHidden" || e.PropertyName == "IsExpanded")
    {
        if (layoutControlGroupItem3.IsExpanded)
        {
            layoutControlGroupItem3.ContainerElement.Items[0].Visibility = Telerik.WinControls.ElementVisibility.Visible;
        }
        else
        {
            layoutControlGroupItem3.ContainerElement.Items[0].Visibility = Telerik.WinControls.ElementVisibility.Collapsed;
        }
    }

}