The issue of the chat function disappearing in the Copilot app can occur due to various reasons, including permission settings and the active state of the chat feature. It's important to ensure that the chat feature is active in the Copilot settings and that you have the necessary permissions to use it. If the chat pane does not show, you may want to check if the chat is enabled in the Copilot & agent capabilities page, as it might not be active by default in some regions.
If the problem persists, consider checking for any updates or changes in your app settings that might affect the visibility of the chat function.
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