If you are having troubles seeing imports / links or possibly point clouds when imported into Revit. The main reason (presuming it’s nothing to do with visibility settings / overrides) is most likely to be that the link is a very large distance away from the model space.
The reason this happens is down to the coordinates imports in your Revit project. For instance your model center point which would be at 0m, where as your link or point cloud import may be thousands of km’s away. This will of course leave you in a situation where, if you zoom to fit, you will see neither your original file or the linked file, as they are so far away from each other that they become invisible unless zoomed into.
It may also be difficult to locate where each file / import is. A good work flow I have been using is to import your point cloud, zoom to fit. Highlight from the bottom left of the screen all the way to the top right. Use the filter option in Revit to filter the elements. Select ONLY the point cloud / linked file which you wish to be imported on top of your model.
Isolate this the selected element and then use the zoom to fit option. Now you should be able to see your point cloud / import in the center of the screen. You can now create a section through the import and then split it up by levels and add elevations etc. You will now be able to acquire coordinates from your import and use them as the project base coordinates