title: add_row in ACF Pro isn't saving repeater values
body: <h2>My Situation</h2>
  
  <p>I'm using <a href="http://advancedcustomfields.com" rel="nofollow">Advanced Custom Fields Pro</a> to store metadata for a post in wordpress.</p>
  
  <p>My posts are created dynamically (not through the administrative interface), which means that I explicitly need to populate metadata using field keys, not field names.  One of my fields is a repeater field with a single text area and another is a standard text area.</p>
  
  <h2>My Code</h2>
  
  <p>The following code is what I call (once per post).  The post is created using <code>wp_insert_post()</code> earlier.</p>
  
  <pre><code>  // Populate "Name"
    update_field('field_566e360961c2f', 'John Doe', $wp_identifier);
  
    // Populate "Sponsors"
    foreach($sponsors as $sponsor) {
  
        // Define "Sponsor Name"
        $new_sponsor = array(
          'field_566e32fb943a5' =&gt; 'Beats and Corn Companye'
        );
  
        add_row('field_566e32bd943a4', $new_sponsor, $wp_identifier);
    }
  </code></pre>
  
  <p>The result of this is that standard text fields populate, and a single "sponsor" repeater item is created, but the value of the sponsor name is blank.</p>
  
  <p>The relevant <code>wp_postmeta</code> data that is generated looks like this:</p>
  
  <pre><code>|   18226 |      71 | name                    | John Doe
  |   19234 |      71 | sponsors                | 1                                                            |
  |   19235 |      71 | _0_field_566e32fb943a5  | Beats and Corn Company                                                                             |
  </code></pre>
  
  <h2>My Question</h2>
  
  <p>What am I doing wrong?  Looking at the documentation for <a href="http://www.advancedcustomfields.com/resources/add_row/" rel="nofollow"><code>add_row()</code></a> this appears to be the correct approach.  Is it possible that repeater fields have a different way of notating keys that I'm not aware of?</p>