title: MongoDB / Mongoose timestamps not updating
body: <p>Schema:</p>
  
  <pre><code>var schema = new Schema({...}, {
      timestamps: true,
      id: false,
      toJSON: {
          virtuals: true,
      },
      toObject: {
          virtual: true,
      }
  });
  schema.virtual('updated').get(function () {
      if(typeof this.updatedAt === "undefined" &amp;&amp; typeof this.createdAt === "undefined") return "";
      var updated = (typeof this.updatedAt === "undefined") ? this.createdAt : this.updatedAt;
      return "Updated "+moment(updated).fromNow();
  });
  </code></pre>
  
  <p>This code <strong>was</strong> working recently - updatedAt for a particular instance comes up as August 24th, however any new edits to the document <strong>doesn't</strong> update the timestamp.</p>
  
  <p>Feels like I'm missing something very silly here.</p>