Another thing you can try is stopping the app rather than deleting it. You double click the home button on the iPad so you get all the active apps showing in a sort of pack of cards across the screen, move sideways until the Naim app is the central one and then swipe it upwards. It will disappear and you then press the home button once. The home screen is back to normal now. Then you select the app normally and it will start. This usually solves problems of the app not seeing rooms or servers.
Once you are used to doing this, it takes only a couple of seconds to do.
Also this isn't a known bug on the app, so it suggests that there is some issue with your network. You could try restarting the Core (so that it gets a new ip lease from your router). The next thing to try after that is turn off the Core, Qb and 272 and then restart your router. Wait until it has fully restarted and then turn the Naim kit on again. Stop the Naim app as I describe above and when all the Naim kit has finished restarting, select the app and all should be ok.