title: Black screen on viewController in IB, Xcode 12.4
body: <p>I'm updated Xcode to version 12.4 (12D4e), MacOS 10.15.7, open my project, and see it:
  <a href="https://i.stack.imgur.com/HdfiK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HdfiK.png" alt="enter image description here" /></a></p>
  <p>All elements lost labels, have black background (don't change from IB) and blue borders. If i add new element on viewController - i get same thing.
  In Simulator and real iPhone all works fine, but in IB - that problem.
  Clean build folder, restart Xcode and MacOS not working.
  Does anyone know how to fix it? Thx</p>
  <p><strong>UPDATE, with solution this problem:</strong>
  I'm rolled back last commit in project and problem disappeared. Maybe, that happens, because i'm used in last commit custom class with @IBDesignable properties and delete him later, before commit on Github and update Xcode. I found similar problem and answer, on this link <a href="https://stackoverflow.com/a/56121110/13110274">https://stackoverflow.com/a/56121110/13110274</a>
  Now all works correctly</p>