Ahhh. I see. So I have broken the alias by moving the files using Finder instead of the internal FCPX management. How should I rectify this? Do I need to delete the moved files on the new drive, and go back and re-copy them using the internal FCPX system? And if yes, how do I use the internal FCPX system to move / copy files from one external drive to another? Have never done that before.