Custom Audio Setup (AirPods Pro A2618, iOS 15.7.1)

I am not able to setup a custom audio profile for my new AirPods Pro.

I have model A2618 AirPods Pro, and am using iOS 15.7.1 on an iPhone 12. The Airpods are generally recognized by the iPhone, and I can see the model numbers in the Bluetooth settings, etc.

However, when I go to Settings -> Accessibility -> Audio/Visual -> Headphone Accommodations

and click on "Custom Audio Setup", I get the following error message:

Headphones Not Supported

Custom settings are only available for supported Apple and Beats headphones.

This seems to indicate that the iPhone, or the iOS, is not recognizing these Airpods properly for the purposes of customization.

Please note that I have read the information on Customize headphone audio levels on your iPhone or iPad - Apple Support, and this page clearly indicates that the new Airpods Pro 2, of which model A2618 should be a member, is included in those that are supposed to be fully customizable.

Any suggestions would be welcome.