Work around: 
 void radRibbonBar1_CommandTabSelecting(object sender, Telerik.WinControls.UI.CommandTabSelectingEventArgs args)
        {
            if (args.NewCommandTab.Visibility == Telerik.WinControls.ElementVisibility.Collapsed || args.NewCommandTab.Visibility == Telerik.WinControls.ElementVisibility.Hidden)
            {
                args.Cancel = true;
            }
        }