title: Missing Android platform(s) detected: 'android-27'
body: <p><a href="https://i.stack.imgur.com/zNW7x.png" rel="noreferrer"><img src="https://i.stack.imgur.com/zNW7x.png" alt="when I use 27 platform I have this error"></a></p>
  
  <p>I update my android studio to 3.1.3 but I cannot use platform 27 now
  when I click "install platform and sync project" it pop up a download window  and then disappear. But the error still exist. SDK Platforms is following:
  <a href="https://i.stack.imgur.com/wMjJ7.png" rel="noreferrer"><img src="https://i.stack.imgur.com/wMjJ7.png" alt="SDK Platforms"></a></p>
  
  <p>expand SDK:<a href="https://i.stack.imgur.com/sVEUA.png" rel="noreferrer"><img src="https://i.stack.imgur.com/sVEUA.png" alt="expanded SDK here"></a></p>