Wild Orc Hunters

[Not.Him.Again]

Wild Orc Hunters are attacing invisible targets. On the quest I drank an invis potion and after that the orc archer attacked and killed my character. I am guesing this is a bug unless you want them to be able to see invis?

[Ommadawn]

It is possible the orc still heard you. Being invisible doesn't make you silent, and I've been ganked by these guys simply because I ran past them invisibly and never saw them until it was too late.

Most likely though, it was a bug where you were already targeted and drinking the invis didn't break targetting. Hitting stealth as well does apparently help here.

[Not.Him.Again]

Ah, yeah. I wasnt moving. I was standing still trying to drink a healing potion. Oh well, thats the way the cookie crumbles some times.

[ExileStrife]

Wild Orc Hunters have regular player-AI where they will attack anything that goes invis and continue to follow and attack it somehow despite not having a see-invis potion.  har har.

[Ebok]

This is covered somewhere else, it has to do with their listen, and It's not getting changed. They will also start shooting at you if you run near them already invisible. Bear this in mind. (though if you run fast enough, they stop getting sneaks in)

[VanillaPudding]

It has nothing to do with listen, mechanics wise, that is simply some sort of RP based excuse. It's a mechanical 'bug' where they won't switch targets after they have one even if said target goes invisible. There are ways to avoid it, but I don't know if they classify as exploits so I won't post that.

[Mort]

It has to do with Listen check, mechanically. The normal perception radius is relatively small. Certain creatures have an enhanced perception radius which makes them more likely to 'hear' you pass invisibly next to them and then start to shoot/attack you which can lead to death, surprise and panic.

The fact that they SOMETIMES not stop to target and pursue you is the bug that is referred.