InvalidEndpoint response returned in 'correctly' constructed API call to `/api/v2/ai_bots/generative_replies`

Does anyone know why the following is failing, with what looks like a weird response?

Request:
  POST {{baseUrl}}/api/v2/ai_bots/generative_replies 

Response:
   {"error":"InvalidEndpoint","description":"Not found"}

Note: 
 

• The call was made in Postman, using a fork of the official Postman collection(https://www.postman.com/zendesk-redback/workspace/zendesk-public-api)
• The setup of the call - especially the form data - (not included here) looks correct.
  • The same auth setup and baseUrl variable used to make the call suceeds for a different endpoint.
• Advanced AI bundle has been purchased for the account