title: Can't write to a knockout observable
body: <p>I am having a very strange bug when I am trying to update a user's address.  I have this simplified address object with two fields, both observables:</p>
  
  <pre><code>stateProvince.name = ko.observable("");
  stateProvince.code = ko.observable("");
  </code></pre>
  
  <p>Now, when I try to update both of these later, this is the effective program execution in dev tools:</p>
  
  <pre><code>stateProvince.name("New York");
  stateProvince.code("NY");
  </code></pre>
  
  <p>but the second line does not actually change the value of the state code.  no exceptions occur, attempting to change it in dev tools does not work, and the strangest part is that everything that fails when changing the code works fine when changing the name.  What conditions could cause a knockout observable from failing to update with no errors?  I am trying to extend an existing codebase but my searching has not revealed anything that would differentiate these two objects.</p>