Yep, been there. Currently I have a CD missing, it's one that came in an oversized sleeve inside a handmade, by the artist, cloth cover. It's not in the oversized CD section, not in the current/to-be-filed section, can't fit into the alpabeticised main CD shelves. By rights, it should be the hardest to mislay given its distinct very colourful cover but nada...
Have you checked inside the Sama Layuca sleeve?