Can't see other than default metadata

Hi there everybody.
By "Editing Metadata Views" I suppose that you could add other metadata to the views accessible via the Inspector, but this doesn't seem the case.
In the attached image, you'll see a new metadata view that I've created, "Complete EXIF", with some field flagged, but as you see in the right part of the image, no field is shown in the view. This is true also for the existing view if I want to see other metadata: I flag them but they're not shown. Any idea about this?
I know for sure that the video files contain exif metadata, as I can see them in Canon Digital Photo Professional software, but I can't even see the metadata fields in FCPX, let alone their content.
Anybody experienced this?
Thanks a lot

I think that is because these particular metadata items are not relevant for the selected clip (a video).
Try selecting a still image and metadata like Focus Distance should appear.