ATV - ZC app, cant see devices on ZC phone, but can on ipad

Hello
4K ATV, Iphone 7plus with ZC app(all updated and current ios etc). Also have ipad
I’ve watched all the videos/read support etc.

I can connect 3 devices, via my ipad to ATV.
ATV on its own works fine and connects to 2 devices.
I have checked WiFi and changed 2.5/5 ghz settings etc.
However, I still can’t connect via ZC on my iPhone. When I click the radio button, I get spinning and then phone icon with an exclamation mark.
My phone can connect to devices via wahoo app and zwift on phone Bluetooth.

I can’t really use the iPad for ZC so if anyone has any ideas how to fix this so I can connect my iPhone I’d be really happy swiping in 2021.

What do you mean when you say ‘click the radio button’? Do you mean turning off the cellular service, or something else?

I think he’s using “radio button” in UI terms, i.e. a pressable button like on an old-fashioned radio.

Yes - it’s the one top left in ATV pairing screen, that forces connection via ZC app, rather than ATV internal Bluetooth