Use attached to reproduce:
- Just search for something and you will notice that the waiting bar does not disappear. 

Workaround:
public RadForm1()
{
    InitializeComponent();

    
    radGridView1.MasterView.TableSearchRow.IsSearchAsync = false;
    radGridView1.MasterView.TableSearchRow.SearchProgressChanged += TableSearchRow_SearchProgressChanged;

}

private void TableSearchRow_SearchProgressChanged(object sender, SearchProgressChangedEventArgs e)
{
    var searchCell = radGridView1.TableElement.FindDescendant<GridSearchCellElement>();
    if (searchCell != null)
    {
        var waitingBar = searchCell.Children[1] as RadWaitingBarElement;
        waitingBar.StopWaiting();
        waitingBar.Visibility = Telerik.WinControls.ElementVisibility.Collapsed;
    }
}