Got the piercing task challenge, went to the bottom area of the whisper outside of Sacra, climbed up the rock formation and killed some of them. It never registered any of the kills.
I used the legendary spear, as well as the Sacraments Sin weapon, just in case it was a bug with the legendary spear, that way I had a backup. It never registered either for the kills.
I went all throughout Sacra trying to kill enemies to get the quest to pop. Never did. I even left the game, came back after a couple hours when things respawned. Tried again. Still nothing.
Also, the legendary spear currently has a bug where when you are looking at it in the inventory, the Rune slot “X” doesnt show the move there. But when you actually use it it still activates for combat