Cannot filter with Operator=@Operator.Contains

@page "/"

<h1>Hello, world!</h1>

<EjsGrid DataSource="@Orders" AllowFiltering="true" AllowPaging="true">
    <GridColumns>
        <GridColumn Field=@nameof(Order.OrderID) HeaderText="Order ID" TextAlign="TextAlign.Right" Width="120"></GridColumn>
        <GridColumn Field=@nameof(Order.CustomerID) HeaderText="Customer Name" Width="150"></GridColumn>
        <GridColumn Field=@nameof(Order.OrderDate) HeaderText="Order Date" Format="d" Type="ColumnType.Date" TextAlign="TextAlign.Right" Width="130"></GridColumn>
        <GridColumn Field=@nameof(Order.Freight) HeaderText="Freight" Format="C2" TextAlign="TextAlign.Right" Width="120"></GridColumn>
    </GridColumns>
    <GridFilterColumns>
        <GridFilterColumn Field=@nameof(Order.CustomerID) Operator=@Syncfusion.EJ2.Blazor.Operator.Contains/>
    </GridFilterColumns>
</EjsGrid>

@code{
    public List<Order> Orders { get; set; }

    protected override void OnInitialized()
    {
        Orders = Enumerable.Range(1, 75).Select(x => new Order()
        {
            OrderID = 1000 + x,
            CustomerID = (new string[] { "ALFKI", "ANANTR", "ANTON", "BLONP", "BOLID" })[new Random().Next(5)],
            Freight = 2.1 * x,
            OrderDate = (new DateTime[] { new DateTime(2010, 5, 1), new DateTime(2010, 5, 2), new DateTime(2010, 5, 3), })[new Random().Next(3)],
        }).ToList();
    }

    public class Order
    {
        public int? OrderID { get; set; }
        public string CustomerID { get; set; }
        public DateTime? OrderDate { get; set; }
        public double? Freight { get; set; }
    }
}