Conversational Messenger returns PERMISSION_DENIED for anonymous access after Conversational Agents migration

Google Cloud Build with AI Conversational Agents (Dialogflow CX)
1

The embedded Dialogflow / Conversational Messenger (df-messenger) widget on my website returns “Permission denied” for every user message. I’d appreciate help restoring anonymous (unauthenticated) access.

Product: Conversational Agents (Dialogflow CX) - Conversational / Dialogflow Messenger

Agent: a global, generative Playbook-based agent (“ERP Buddy”)

Steps to reproduce:

  1. Publish agent → Conversational Messenger → Access = Unauthenticated (anonymous), no domain restriction, Environment = Draft.
    1. Open the built-in “Try it now” preview (on Google’s own console page).
      1. Send any message.
    3. Actual: the bot replies “Permission denied.”
    4. Expected: the agent replies normally.
  3. Key evidence that this is NOT a website/domain/hosting problem:
    • The agent works perfectly in the console simulator (authenticated).
      • Billing is a paid, active account.
        • It fails only on the anonymous/unauthenticated path, and it fails even in Google’s own “Try it now” preview - so it is not related to my embedding domain.
          • Disabling and re-enabling the Conversational Messenger integration did not resolve it.
            • This started after the forced “Dialogflow CX → Conversational Agents” migration.
          • Ask: How do I restore anonymous (unauthenticated) access for the Conversational Messenger integration on this agent? Is this a known issue caused by the migration? Thanks!