GridViewComboBoxColumn doesn't work properly on edit

The ItemsSource of GridView:

ProductID,

Name,

Code,

ProductTypeName(GridViewComboBoxColumn)

The ItemsSource for GridViewComboBoxColumn :
ProductTypeID,

ProductTypeName

The problem is when I select another item from the ComboBox after double clicking the column in the RowEnded event, it doesn't give me the Updated ProductTypeID, instead it always gives me the ProductTypeID which was first bound when I loaded the GridView. I think there is some issue with the Bindings

Here is the Xaml:

<telerik:RadGridView.Columns>
   <telerik:GridViewDataColumn x:Name="ID" 
        DataMemberBinding="{Binding ProductID}" 
Header="ID" 
IsReadOnly="True" 
        IsVisible="False"/>

    <telerik:GridViewDataColumn x:Name="Code" 
        DataMemberBinding="{Binding Code}" 
        Header="Code" 
        IsReadOnly="False" />

    <telerik:GridViewDataColumn x:Name="Name" 
        DataMemberBinding="{Binding Name}" 
        Header="Name" 
        IsReadOnly="False" />
                   
<telerik:GridViewComboBoxColumn DataMemberBinding="{Binding ProductTypeName}"
        UniqueName="ProductType"
        SelectedValueMemberPath="ProductTypeName"
        DisplayMemberPath="ProductTypeName"
        Header="ProductType"/>

    </telerik:RadGridView.Columns>
</telerik:RadGridView>