When an agent accepts the chat, the page loads a blank screen

When a chat is initiated and routed to an agent, the agent sometimes sees a blank chat window. This behavior may also occur in Messaging for In-App and Web when embedded in a Lightning Console.

Steps to reproduce:

1. Configure an org with Chat and Omni-enabled
2. Configure an agent that can receive chats in the lightning console
3. Configure a test chat button that can submit chats to that agent. Configure an auto-greeting to help illustrate the issue
4. Start a chat and accept it with the agent

5. In the JS console on the agent side enter: $A.getComponent('<chatBody component global id>').set('v.chatDataFetched', false); You can get the global id either with the Lightning plugin, or by placing a breakpoint in the ChatBody controller/helper code and calling cmp.getGlobalId()

6. The chat body should disappear in the UI
7. Send some messages from the visitor
8. Now run the same JS snippet, but pass true for the value instead
9. The chat body will reappear, but will only show the auto-greeting
10. Refresh the browser and you should see all messages shown in the body
    
    This is one of the ways to reproduce this issue, but customers encounter it in other ways as well, like seeing
    ‘Transcript isn't ready' messages at the start because they have automation running. The same issue occurs when messages are sent during this time