Seriously, Larian, the enemy needs some way to deal with invisibility; otherwise, when we can finally get Greater Invisibility, it will be possible to walk up and just keep wailing on things until they die, no tactics or strategy needed. "I killed an ancient dragon using a dagger" sounds fantastic until you realize it was an hour-long boring grind because the dragon wouldn't attack or move.
Yes. Stealth combat right now is just ridiculous because the enemies don't do a bloody thing. Would definitely be the same with invisibility.
There is a partial stealth-breaking mechanism implemented, but it is, at best, buggy as sh**.
If the enemies have already seen you and you are stealthed in an area that enemies can get to line-of-sight of within one turn, sometimes they will move up and find you. It's rare, but it happens. I think there's a visual cue to 'the enemies know where your stealth point is': Notice that sometimes when you go into stealth, you get a highlight/beacon on you. I think that's a clue that the enemies might be able to find you. I am not talking about the 'stealthing without cover' marker, that's different. If you get the beacon and then move, the beacon stays in the same place, which reinforces my belief that the game does have some mechanism for looking for stealthed characters. But the discovery isn't consistent or frequent.
Invisibility is flat-out broken. You can walk up until you are threatened, go invisible, and not move thereafter. The enemy never attacks, never uses opportunity attacks, and, unless there is another force at work, never moves.
