title: UIStackView zero height although I have content in it
body: <p>I have UIStackView in UITableViewCell and have four long text labels in it.
  In first load I show only first label with 44 height in cell and hide other three and StackView shows properly.Then when I click on tableViewCell I need to expand cell and show other three labels. I show them and reload TableView but my StackView has zero height after that and all four label have zero height too. I hit this problem only with IOS 10.1 and when I use labels with short text StackView work well.</p>
  
  <p>This is my code:</p>
  
  <pre><code>func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
      var cell  = tableView.cellForRowAtIndexPath(indexPath) as! AboutUsTableViewCell
      cell.firstLabel.hidden = isExpanded
      cell.secondLabel.hidden = isExpanded
      cell.thirdLabel.hidden = isExpanded
      isExpanded = !isExpanded
      tableView.reloadData()
  }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/u4xBA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/u4xBA.png" alt="This is my xib"></a></p>
  
  <p><a href="https://i.stack.imgur.com/RDhiZ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RDhiZ.png" alt="This is how looks like before click"></a></p>
  
  <p><a href="https://i.stack.imgur.com/24GSUl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/24GSUl.png" alt="This is after click"></a></p>
  
  <p>Thank you all!</p>