Full credit to User RO.OTHORICK from the DJI forum for this fix and following text
Before connecting to the drone’s WiFi network, first put the phone in airplane mode. Then, enable WiFi manually (keeping airplane mode on — this is important) and connect to the drone’s network. NOW the app will find the drone and start the registration process. During registration, you’ll get to a screen that says “No Wi-Fi Connection” at the bottom. Here you’ll have to connect to a standard WiFi access point with Internet service — cell data doesn’t seem to cut it for some reason. It will successfully register the drone and you’ll finally have the “Camera” button… which will seem to work, but not really.
Why? Well, on affected phones, when flying, you’ll have to keep your phone in airplane mode the whole time, connected to only the drone and maybe some Bluetooth devices. This may cause problems with Follow Me mode since the phone won’t have access to A-GPS in airplane mode — haven’t tried it yet.
To update the firmware, you have to do the same “airplane mode then WiFi on” dance, AFTER downloading the update, but BEFORE installing it.