I used weapons to attack the wolf pack, but there was no hit effect at all. Even when I shot at the ground, there were no bullet marks, as if the weapon was firing air.

I've triggered it twice. The first time was on a community server. I respawned by the sea, picked up a couple of weapons just randomly, and fired at zombies, but nothing happened. I thought it was a safe zone in the community, so I didn't pay much attention. This time was my second experience. When I was being attacked by a pack of wolves, I used my shotgun, rifle, and pistol, but none of them did any damage, and there were no signs of bullets being fired. I suspect the bullet model might be missing?

Hit successfully and killed them