title: Knockout foreach not matching length
body: <p>I'm having trouble displaying items from a knockout observable array.</p>
  
  <p>The code below displays a length of 3 (so I know there are elements), yet the foreach does not display any rows.</p>
  
  <pre><code>&lt;label data-bind="text: Data().length"&gt;&lt;/label&gt;
  &lt;table&gt;
      &lt;tbody data-bind="foreach: Data"&gt;
          &lt;tr&gt;
              &lt;td &gt;woot&lt;/td&gt;
          &lt;/tr&gt;
      &lt;/tbody&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>The result of </p>
  
  <pre><code>&lt;label data-bind="text:  ko.toJSON(Data)"&gt;&lt;/label&gt;
  </code></pre>
  
  <p>is: </p>
  
  <pre><code> [ { "Description" : null,
      "DeviceId" : "fake1",
      "DeviceType" : null,
      "Policy" : null
    },
    { "Description" : null,
      "DeviceId" : "fake2",
      "DeviceType" : null,
      "Policy" : null
    },
    { "Description" : null,
      "DeviceId" : "fake3",
      "DeviceType" : null,
      "Policy" : null
    }
  ]
  </code></pre>
  
  <p>Any advice much appreciated</p>