I took your suggestion of adding the Volumes into the sources.xml and that worked fine for allowing me to see the HDD and the various media folders in it. In File Manager, I can click on any media file and it will play.
Here's the source.xml file:
http://pastebin.com/d2027bcab
However, when i go to Watch a Movie, or Listen to Music, etc. and try to rebuild the databases, when I go to File Mode (since the databases are empty right now nothing shows up on Library mode) the only two options I still get are VIDEO PLUGINS and ADD SOURCE.
When I go to ADD SOURCE and try to browse to the HDD it still doesn't show it (and this is previously where I would direct it to the HDD via the /mnt option. My only options are DVD Drive, HDHomrun, Home Folder, Replay TV, SAP, UPNP, Video playlists, video plugins, SMB, Add network Location.
I also have 'Update Library on Startup' enabled, but nothing happens