I found the media. It only shows up when filtered by title. Apparently either the .ogg format does not have info encoded to the file to determine other info such as album or artist, or the linux mce software doesn't scan for it. I need to look into .ogg more.
Unfortunately, UpdateMedia does not yet have the capability to read tags for OGG or FLAC files. This is pretty frustrating, as I have a lot of my music in FLAC format and I don't really feel like hand-coding information for a bunch of music. When Pluto/LMCE rips a FLAC or OGG file, it creates a separate file that contains the title, artist, etc, in what I think is an MP3 tag format. It then uses this file to identify the track. The long-term solution is to fix UpdateMedia to correctly read Vorbis tags and populate the database. I already submitted a patch to get LMCE to add the correct data to OGG and FLAC files when it rips them from CD. I think this is in the current release.
The short-term solution will probably be to write a script/program that reads Vorbis tag information and creates the file that LMCE uses to identify the track. This would have to be run each time you add new music from outside LMCE. If any enterprising coder wants to take a crack at it, I'm guessing there are a lot of people with OGG/FLAC music that would be very appreciative. Otherwise, that's next on my list once I get the Insteon integration mildly stabilized and integrated.