RadzenDropDown can't search by StartsWith

Hi, I have a problem with RadzenDropDown. I try to use attribute FilterOperator to search with start letter like this:
<RadzenDropDown TabIndex="-1" Style="width:99%!important;" AllowClear="true" TValue="short" FilterOperator="StringFilterOperator.StartsWith" Placeholder="@data.Kari_kan" FilterCaseSensitivity="FilterCaseSensitivity.CaseInsensitive" AllowFiltering="true" @bind-Value="@data.Kari_kanCode" Data="kankamokuLst" TextProperty="Selected" ValueProperty="Code" >

When i enter from keyboard, it does not show any suggestion results.
Hope you guy can help me.
Thank you,

The second DropDown in this demo is exactly with StartsWith: