Hello! Member of the API team here. We're unable to find issues with the /v1/models endpoint—can you share more details about your request? Feel free to email me at suzanne@anthropic.com. Thank you!
$ curl https://api.anthropic.com/v1/models --header "x-api-key: $ANTHROPIC_API_KEY" --header "anthropic-version: 2023-06-01"
{"type":"error","error":{"type":"not_found_error","message":"Not found"}}
Edit: Tried creating a different API key and it works with that one. Weird.