When I insert a Revit file inside of Navisworks through the RVT file itself, it inserts correctly and in the correct coordinates, but it is not displaying the "Volume" property. My revit model is a Generic Model.
Depending on what your Selection Resolution is set to, you won't see all the properties of the object. Try changing your Selection Resolution to "First Object" and see if that helps see the appropriate properties.
Or, don't change the Selection Resolution, just select the object, go to the Selection Tree and choose the different "levels" of geometry until you see the properties you are looking for.
See the attached image...if I select anything else other than what I have selected in the Selection Tree, I won't see the proper Properties, thus not seeing the Volume.
Okay, go to your Options in Navisworks, then go to File Readers. Click on Revit, then makes sure the "Convert element properties" is checked. I believe this is turned off by default.
Okay, what about the top option "Convert element parameters", what is that set to?
If you haven't tried this yet either, especially if you change any settings, delete the NWC that's been created after you opened the Revit file in Navisworks. Open a new Navisworks file and bring the Revit file in again.
