It mentions this in the game when you get them. It says it follows you around if you move too far. I left one out in the wilderness and used rift travel to return to town and it stayed where I put it, so it CAN be used as a beacon in certain conditions. Maybe it "follows" you if you put it in a dungeon or something? Like, it can only be used in the overworld? (I haven't been to the Black Cove yet, so I'm not sure if what I'm saying makes sense in that regard).
