Webform Select List using Existing Contact

I have used "Existing Contact" Field in the Webform.

I want to list few contacts using select box instead of AutoComplete using Filter.

Edit Field show different Widget to show the contacts, one of theme is ‘Select List’.

Once you save the ‘Select List’ Display format, front end form does not display/generate select element and its options.

I am using Laster Webform CiviCRM module under Drupal 8.

Anybody have idea of this, I tried same thing D7, its not working there too.