The Diagnostic Navigator is a tool to help you examine potential problem areas that are identified with the Mesh Diagnostic tools. The Diagnostic Navigator is only visible when you have run a Mesh Diagnostic tool.
To activate the Diagnostic Navigator, run one of the Mesh Diagnostic tools, found on the Mesh tab.
When you activate a Mesh Diagnostic tool, it opens in the Tools tab of the Study Pane. Click the Show button, and the Diagnostic Navigator appears on the far right of the ribbon.