TokenBox cuts an input string if Properties.NullText is set

I have a TokenBox on my FormLayout:

C#
@model SampleProj.ViewModels.MyClass  

@Html.DevExpress().FormLayout(settings =>  
{  
    settings.Name = "formLayout";  
    settings.Width = Unit.Percentage(100);  

    settings.Items.AddGroupItem(group =>  
    {  
        group.GroupBoxDecoration = GroupBoxDecoration.None;  
        group.Width = Unit.Percentage(100);  

        group.Items.Add(item =>  
        {  
            item.Name = "formLayoutGroupTokens";  
            item.NestedExtensionType = FormLayoutNestedExtensionItemType.TokenBox;  
            var tbSettings = (TokenBoxSettings)item.NestedExtensionSettings;  
            tbSettings.Properties.NullText = "Enter text";  
            tbSettings.Name = "Text";  
            tbSettings.Properties.ValidationSettings.Assign(SampleProj.ViewModels.ValidationHelper.CommonValidationSettingsRequired("Field required at least one token"));  
            tbSettings.Width = Unit.Percentage(100);  
            item.Caption = "Tokens";  
        });  
    });  
}).GetHtml()  

But when I copy some text with comma or semi-colon separators from clipboard, the output token box shows only first item from text.
When I continue press ctrl+V, token box add next item from text but only one:

Text:
111;222;333;444

Output:

1. 111x
   -> ctrl+V
2. 111x 222x
   -> ctrl+V
3. 111x 222x 333x
   -> ctrl+V
4. 111x 222x 333x 444x

Now I press again ctrl+V:

5)111x 222x 333x 444111x

Then after pressing ctrl+V token box will ignore anything from input text.

What I should do to correct such behavior?

Thanks a lot!