Freezing Pulse not piercing after splitting with Fury Valve

I'm running a Freezing Pulse build with Fury Valve and Pinpoint support. This gives me 4 splits at the start, and since Freezing Pulse innately has pierce, I expected the projectiles to pierce targets after doing the initial split. However, this doesn't seem to be happening. It's a little bit hard to see in white packs, so here's a clip where I fire multiple shots at a blue pack:

https://clips.twitch.tv/CovertCloudyMarrowPermaSmug-Fv8Y3mR05CTVxVM_

It's pretty clear that there's no projectiles emerging from the pack, which I'd expect to see if they had pierce. Is this intended behaviour with Fury Valve, or a bug?