Have tested on multiple devices, both iPhone and iPad. No issues connecting Bluetooth to device and on Tacx app. Nothing comes up on Zwift app. Everything is updated.
You need to make sure the Neo is not connected to anything before attempting to pair with Zwift. You do not need to add it to the iPhone or iPad Bluetooth device list. If you did, remove it. Also make sure you force quit the Tacx app(s). Power cycle the Neo. Once nothing is paired to the Neo, open Zwift and proceed to pair the Neo via Bluetooth.