Hecarim's E Still Procs on Target In Poppy's W Despite Being Denied

I'm a Poppy player and most people who at least know what Poppy's W(Steadfast Presence) does, is that it will deny any form of dashes. It can stop Ekko's E, Lucian's E, Aatrox's E and so forth. It also stops the attacks that come with them. But for some reason when it comes to Hecarim and his leap, it will only stop him from actually getting on top of the target, however it will still deal damage to the said target, and will sometimes still perform the knockback. Is this intended or is this a bug since no one else's dashes that can be stopped will still proc their damage/affects.