Have the same problem when using Vamp Ultimate (bat swarm) with the invis upgrade. Haven't tested this problem in PvP, but I know mobs continue to attack you if you go invis with it.

When I use dark cloak on my nightblade now NPCs will often keep attacking me. It could glitch earlier but after last patch it is happening very often.

Yeah it's annoying as heck. My Shadowy Disguise is almost useless in NPC combat. The NPC's just see me anyways half the time and keep mashing away at me.

Well in my instance, I will hit Shadowy Disguise. Normally, the NPC should lose sight of me because I become invisible, however, now I can move around while invisible and NPC keeps following or facing me. It's not happening every time and seems completely random, but it's only happening while being engaged in combat. They aren't seeing me at all while invisible when out of combat.

EDIT: I read somewhere that group dungeon bosses are supposed to act like that and that I have no issue with. Normal skeleton and humanoid mobs shouldn't act like this imo.