Can't sort Posts on Emberfire

I am trying to sort my posts so that the most recent appears on my blog central page. I am able to manipulate by author and title, but I am really trying to get the most recent published date to appear at the top of the page. Is there something I need to do with the sortproperties on the controller? I've tried messing with the "limitToFirst" and "limitToLast" as well. I also tried "publishedDate" instead of published, but published appears in the "Ember Inspector", so I think published is what I want. Here is my code below:

controllers/post.js 

import Ember from 'ember';

 export default Ember.Controller.extend({
 sortProperties: ['published'],
 sortAscending: false, // sorts post by timestamp
 actions: {
 publishPost: function() {
  var newPost = this.store.createRecord('post', {
    title: this.get('title'),
    post: this.get('post'),
    author: this.get('author'),
     published: new Date().getTime()
  });

  newPost.save();
   }
  }
});

models/post.js

import DS from 'ember-data';

 export default DS.Model.extend({
 title: DS.attr('string'),
 author: DS.attr('string'),
post: DS.attr('string'),
published: DS.attr('number'),
 publishedDate: Ember.computed('published', function() {
return moment(this.get('published')).format('MMMM Do, YYYY');
 })
});

route/post.js

import Ember from 'ember';

export default Ember.Route.extend({
 model: function() {
  return this.store.query('post', {
    orderBy: 'publishedDate',
    limitToFirst: 10
 });
}
});

template/blog.js

 <h2>Below are your Latest Blog Posts</h2>

 <div class="col-sm-8">
    
    <div id=blogPost>
        <div id='published'><p>Published:  </p></div>
        <div id='title'><p>Title:  </p></div>
        <div id='author'><p>Author:  </p></div>
        <div id='body'><p>Post:  </p></div>
    </div>
    
  </div>
</div>