Live Listen option greyed with AirPods Pro

Just purchased AirPods Pro 2; have iPhone 13, updated with current fw. Charged the AirPods, synced them with the phone, all good. Except live listen is greyed out. Tried uninstalling and reinstalling the live listen application, tried powering off and on the phone… nothing works. Some help would be greatly appreciated 😁

[Re-Titled by Moderator]