Can’t use watch or Mobile connect app (iPhone) to configure WiFi on Fenix 5 Sapphire

I’m trying to configure WiFi on a Fenix 5 Sapphire without using Garmin Express (I don’t have a windows device).

The watch is on the latest firmware (7.0), I’ve synced it with Mobile Connect multiple times (as mentioned in the release notes), but when I go to Settings -> WiFi on the watch, it shows the message “Setup WiFi using Garmin Connect Mobile or Garmin Express.” I cannot find any option on the Garmin Mobile Connect app to set up WiFi on the device. The device help on Garmin’s site has a video of how to set up WiFi using Garmin Express, but nothing about the mobile app.

What am I doing wrong?

Thanks, Ian.

Full version numbers:

Watch: Fenix 5 Sapphire (Shown as “fenix 5, WiFi” in the connect mobile app; Firmare 7.00 (e112826)
Phone: iPhone 7; iOS 11.1.2
Mobile Connect App: 4.1.4.2