While all my flights are showing up correctly in the website and the app, the web interface is just poorly designed as pointed out above.
The Manage Booking button loads the booking details in the same browser tab if you want to view or make any changes such as seat selection, special meals etc. and there is no option to 'return to the bookings page' after you have done so, meaning pressing the back button repeatedly to take you back to the Bookings page and at one point it said "Session Expired", having to log in again, authenticate etc. - frustrating ! Navigating between pages without a clear way to return to the previous section is incredibly annoying.

Another issue is the car rental bookings I made through NZ do not display the correct dates on the website but I have confirmed that the correct dates are on the rental company's system.