title: UIButton Title not showing inside UIStackView
body: <p>I created a <code>UIStackView</code> with a <code>UIImageView</code> and a <code>UIButton</code>. The text inside of the <code>UIButton</code> won't show. I can tell that <code>autolayout</code> works because the background and the selection of my <code>UIButton</code> both work properly.</p>
  
  <p>The title always disappears when I have the constraints on. I set the <code>image</code> to <code>0/0/0/0</code> without margins and aligned the button to the image's edges. </p>
  
  <p><a href="https://i.stack.imgur.com/u4W2a.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/u4W2a.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/zGTX0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zGTX0.png" alt="enter image description here"></a></p>
  
  <p>Has anyone run into this or knows how to fix it?</p>