I have updated the agent "Not available" message on the Chat Queue UI . However, is still displaying the old message when going to Chat in Service Portal
Confirmed on Orlando
Make sure to set the "No Agents Available message" in Chat Setup will display for all queues:
No Agents Available Message that users see when a live agent is not available. For example: "No agents are available at the moment. Please try again later."
Note: You can define only one agent availability message, which is displayed for all the queues in your instance.
Setting the "Not available" in a chat queue will only display when opening a chat queue directly
In the filter navigator go to Collaboration -> Chat Setup and in the "No Agents Available message", fill in the message you would like to display to users when chat is not available.