Xcode Storyboard issue - Button Bar Button only appears at the bottom of a TableViewController

I have tried creating the issue you are facing with bar button at bottom. It’s not an issue or Xcode bug.
But in new Xcode when you use segue to ’Show (e.g. Push)’ then in next view you won’t get navigation bar.
You need to add navigation bar and then add bar button item to navigation bar. Hope your problem will be solved.

I had the same issue and fixed it by simply selecting the view controller and changing the "Top Bar" to "Opaque Navigation Bar" from Inferred. This let me add the Bar Button Item on top.