Due to you having CarPlay disabled or your not connected via the USB ports with your cable. If CarPlay is set to active in the APIM settings and you are plugged in with a USB to lightening cable to the factory USB, then there is no way to use factory nav. Only way is to have CarPlay disabled on the APIM, using a different power source than the factory USB ports or you are using an iPhone 4s or later that don't support CarPlay.