Ok I figured it out. Problem fixed. This has nothing to do with debug or release build configuration. UIView in question has children views that have userInteraction enabled only in debug mode. In both debug and release, the touch events are handled by the parent. I guess exclusiveTouch needs to be set on the view in the hierarchy that first intercepts the touch events even if it passes them up. In our case that's the parent in release mode but the child in debug.

Thanks for updating the thread @tf1962!

@joamafer, your point is valid but I think there is a bug here: When I programmatically position a UIBarPositionTopAttached UIToolbar at the top of an iPhone 12 mini with the origin.y position set to the top of the safe area, the automatic extension of the bar's background color under the status bar is 6 pixels shy of reaching the top of the screen on the simulator.

Has anyone got ahold of a physical iPhone 12 mini and been able to check that this bug (status bar 44pts but top safe area 50pts ) is a simulator only issue? It's still an issue in Xcode 12.2.