It does seem to be greyed out, and using sync to device does seem to sync the file over to my player.
Doing a quick install of the portable version, it seems that there are a lot of files missing from the library (standard showing 12,001 tracks, portable showing 13,544 tracks). So it seems to be an issue with the database maybe? Making a new library with the main one has now reduced the library to 10,854 tracks.