Ants use oleic acid to identify other ants as dead, which is also commonly found is plants, although usually not in any notable concentration until we press the plant for oil. Trix use canola oil which contains a lot of oleic acid (compared to other oils, it's not objectively a lot). I wonder if something in the cooking process or combination with one of the other colors or flavors makes it enough to mess them up.
Skimming a research article it looks like oleic acid isn't what they use to mark the burial pile, just what goes in the pile.