Trapper trap hitbox is too small
Survivors can just run around the traps in loops unless you place it in a very tight spot, which is usually only directly at the pallet. The problem with placing it there is that survivors can just drop the pallet making the trap completely useless. This is a major problem because trapper only has 2 traps, so after placing 2 traps, he becomes a M1 killer.
Comments
Sounds like you've placed the trap directly below where the pallet is. For me killers place it on one side of the pallet so when it drops it guarantees a grab.