title: Safari Web inspector is blank
body: <p>I try to use the Web Inspector to debug a remote iOS app.</p>
  
  <p>The 1st time I use the Develop menu, the window does not open.</p>
  
  <p>The 2nd time, the window opens but is empty.</p>
  
  <p>Any idea please?</p>
  
  <p>(macOS 10.12.6)</p>
  
  <p><a href="https://i.stack.imgur.com/iazf3.png" rel="noreferrer"><img src="https://i.stack.imgur.com/iazf3.png" alt="Empty window"></a></p>