After the latest update, Bungie partially fixed the bug with Necrotic Grip (whilst using the Exotic Gloves, or the Exotic Class Item with Spirit of the Necrotic, Melee Abilities weren't properly activating their effects, such as Arcane Needle not creating Tangles, and not activating Devour with Feed the Void). Now, it will sometimes activate it, but it is still very unreliable. For some reason, I am seeing this more whenever I'm in a public area with other Guardians, leading me to believe that it might be network-related. It doesn't occur all of the time, but about one third of the time when in a public zone.