First I must say it seems Apple has changed the default behaviour of tvOS Tab Bars in tvOS 13. Before they used to disappear scrolling down, now they are fixed on top. This is described in UITabBarController:
tabBarObservedScrollViewproperty to the appropriate scroll view. In iOS, the tab bar always stays pinned at the bottom of the screen.
I really preferred the old way. Anyhow..
My issue is that in Xcode 11 beta 5 in a UITabBarController UITabBar doesn't appear anymore in IB. I see that in the prototype app I was developing and it's the same creating from scratch a tvOS Tabbed App (I wanted to attach a picture but I am not sure how). The UITabBarController in IB is empty. Opening the same projects with Xcode 10.3 the UITabBar show.
I have reported this in a BR, still I'd like to be sure it isn't me doing anything wrong or if something is wrong with my Xcode beta installation, because I had to delete it and reinstall it again since it kept crashing opening any storyboard. Thanks.