Why aren't Chat tickets being assigned?
This often happens when an agent's role is set to chat-only, which means they don't have permissions to be assigned tickets in Support. This restriction can be found in user profile under Roles > Chat-only Agent. If the agent permissions are setup correctly and the issue persists, check to ensure that the ticket is answered by the agent and not an automated response. For more information on user roles, see Setting up Zendesk Chat in Zendesk Support.