Select not filled when it is hidden

[mdmoura]

Hello,

I have a select which is inside a hidden div:

<div class="panel">
  <form id="form" method="post" ng-submit="submit">
    <select ng-controller="CountryController" ng-model="model.country" ng-options="country.Id as country.Name for country in model.countries">
      <option value="">Country</option>
    </select>      
  </form>
</div>

div.panel {
  display: none;      
  overflow: hidden;
  position: relative;
}

Because it is hidden the select is not filled ... If I do not use selectize then everything works fine.

Any idea how to solve this?

Thank You,
Miguel