If you’re running into the issue of not being able to export from your Autodesk Revit to a Navisworks NWC, you might need to load the Navisworks Exporter for your version of Revit.

Below you can see what Revit looks like before the Navisworks Exporter is loaded and then after it is loaded. After the Navisworks Exporter is loaded into your Revit program you will be able to export to an NWC from your Addins tab (last image).

Navisworks Exporter