RadzenDropDown DataGrid readonly not working

RadzenDropDown DataGrid readonly not working.

<RadzenDropDownDataGrid Data="@(getCasesForEV_CaseResult)" ReadOnly="true" DefaultValue="@(caseevent.EV_Case)" TextProperty="Case_Name" ValueProperty="Case_ID" Placeholder="Choose Case" ShowSearch="false" style="width: 100%" @bind-Value="@(caseevent.EV_Case)" Name="EV_Case">