Not sure if this is a "bug"; may be more of a feature but I have noticed some files missing in my database, certain albums have tracks missing.

Before I went to look at the ID3 tags, the first one I found missing was titled "Intro". On a hunch, I changed the track name and rebuilt the database and it included the song.

Is there a clause in the database building that omits any tracks titled "Intro"? And if there is, is there a way to disable this?

Also, what clauses (if any) are there at database building time that would cause it to skip the adding of a file to the database?

eJukebox ignores files under 350K when its looking for files to add to the database. The reason for this is so eJukebox does not pickup sound effect files. To get around that you can drag those files to the playlist to get them added. Also the next update v4.99.91 will change database setup so that there is no size requirement when the word "intro" is in the files name.