Game mode: [Online]
Trying to get the Trap Journey step, I decided to give it a try on a rhino in the Savannah area. Much to my dismay, even though I had him chase me around the spot for several minutes and definitely seeing him walk directly on top of the mine, it did not trigger until I stepped on it myself, which did not give me the Journey completion anyway (although it did damage the rhino as well as myself).
Steps on how to reproduce issue:
1.Spend a bunch of resources to make a mine
2.Place mine near Rhino
3.Aggro Rhino and lead him to the mine, carefully avoiding setting it off yourself
4.Become annoyed that the mine is not detonating with a 2-ton Rhinoceros standing on top of it