Claude31, your answer did put me on the right track. I realized that the real issue is that I don't think storyboards support compositional layouts just yet, and when you put a cell/view in a storyboard, it is somehow tied to the layout. I found that I could get visual design using a nib though, and then this code works: let headerRegistration = UICollectionView.SupplementaryRegistration<HeaderReusableView>(supplementaryNib: UINib(nibName: "HeaderReusableView", bundle: Bundle(for: HeaderReusableView.classForCoder())), elementKind: "header") { supplementaryView, elementKind, indexPath in             supplementaryView.titleLabel?.text = self.sections[indexPath.section].rawValue         }

I know this has been an epic long running thread, but just to clarify: There is still a bug where debug messages from the simulator do not show up in the console app (I see them fine in Xcode's console & have the console app debug/info options on). Also see them if I use the 'xcrun simctl spawn log stream' command line that was posted a couple years back. There is no way to do filtering of os_log messages inside Xcode, that is only supported in the console app (where they don't show up due to the above issue) Thanks in advance! Just trying to decide if I want to invest in OSLog now. -pj

Yeah I have the same issue...haven't found a solution yet. I am hoping it is just a quirk of beta.