I am attempting to turn an older PC into a home media server with Ubuntu 12.04 using Plex Media Server. I have a newer WD 2 TB external USB HD with all of my media on it. I can not for the life of me figure out why Plex will not recognize the files on this hard drive. It shows the external as there, Ubuntu shows the files and allows me to play them, view them, etc. Plex shows the name "External". But when I click it, it is 100% empty and shows nothing to add. I can access the files on the external through file sharing just fine, on my windows computers but would love to be able to use Plex for streaming with our Roku. I am fairly new to Ubuntu, I have used Plex with the same HD on Windows and it worked fine. I have read multiple articles on this and nothing seems to be doing the trick. How can I solve this?