Values in autocomplete field are not saved

[nabeta]

I'm trying to enable autocomplete in a creator field on my berlin2018 VM.
https://github.com/samvera/hyrax/wiki/Autocomplete-in-Hyrax

I created app/views/records/edit_fields/_creator.html.erb as the following.

<% name_authorities = Hyrax::NameAuthorities.new %>

<%=
  f.input key,
  as: :multi_value,
  input_html: {
    class: 'form-control',
    data: { 'autocomplete-url' => "/authorities/search/loc/names",
      'autocomplete' => key }
  } ,
  required: f.object.required?(key) %>

<!-- comment out this line to make this form work properly?? -->
<%= f.input key, collection: name_authorities.select_active_options, label: false %>

Autocomplete works as I expected. The problem is that the value I entered into the creator field is not saved if the last line of this template exists. When I commented out the line, the values were saved successfully. Is it a bug, or am I missing something else?