Enemy keeps respawning

Ogham Farmlands, decrepit mercenary normal mobs. Upon dying, maybe a second or two passes, and then the mobs respawn on full health and attack again. No special animation, the corpse just disappears and they reappear on full hp.

Almost the same thing happening to me. Cemetery of the Eternals, about 5 of the ghouls keep jumping up as soon as their health goes down.

Happened to me on two separate occasions. The first was in the desert and again when I rerolled a new character in act 1. Two of the monsters would keep respawning a second or so after dying and have full health and instantly start attacking no matter how many times I killed them. The desert one happened when I played solo and the second time was when I played with a friend.

Observed the same on multiple occasions in all acts.