Sorry to clarify: you hit "back" after traversing from the summary but it doesn't go back? If so, that's a bug!

Or do you mean that doing the browser navigation of "back" should bring you to the summary (initial page)?

Sorry for the confusion! Missing browser navigation is the problem. The virtual back buttons you put in the top left are working as I'd expect browser nav to do. I keep trying to go back, it would feel so natural.