Peninsula: The Pits Pathfinding failure.

ForSerious

There are a few locked doors with levers next to them to unlock an open them.
My character does not have any unlock skill, so I really want to use that lever—but the pathfinding forces him to try and walk to the other side of the lever that is facing the wall. Anyway he can never walk through the wall, so he never is able to pull the lever.

I remember the pathfinding used to be pretty good before they added body-blocking.

Kind of related but probably needs its own bug report: I keep getting into the situation where my character is getting attacked from two enemies that are far enough away that he needs to move closer, but he can't decide which one to go to, so he just sits there facing one than the other until I intervene.

Melkior

The levers have a bug where their default visual setting when placed is "on" but the lever registers as "off." If the animation is then activated to make the lever turn "on," you'll see it quickly jump to the "off" position before moving normally back to the "on" position. This means that often, module builders will place the levers incorrectly so that the "front" faces the wrong way. I believe that it's still possible to move the levers, but your PC has to be standing right next to the lever so that it doesn't need to move to the lever at all. Module builders need to be aware of this problem since it's possible to fix it by manually setting the lever state to be "deactivated" after placing it, so that the lever is correctly set when the module loads.

The other one has been a problem since the earliest days of the game afaik. The auto-retaliate only works with enemies who are within melee range and doesn't work with enemies out of melee range. I believe that if the PC is already in combat and is within perception range of the further enemies, the PC will automatically go after them once finished dealing with closer enemy but won't go after them if not already in combat when attacked from afar.

I believe that if the enemy attacking from afar are outside the PC's perception range, this will also cause the PC to just stand there being hit by arrows or spells unless told by the player to go and attack the enemy. The player's vision covers more area than their character's perception range does.

ForSerious

With older pathfinding, there were always two side of the objects that could be accessed. That seems to have been removed—but only sometimes. That same lever model can be accessed from both sides in other modules.
The pathfinding really was much better when there was no body-blocking and you could walk through doors once opened. I find it annoying that the doors only appear and become clickable if your camera is angled just right. They should revert those changes.

As for the indecisiveness of my character, I have not seen that in awhile. Maybe it's been fixed. I still get the issue where somehow the melee range is different so some melee enemies will continue attacking but my character judges them to be out of melee range and just gives up. Sure enough, when I click on one of the attacking enemies, my dude has to move closer then starts attacking.

That reminds me. I HATE how the visual pathfinding is not always in sync with the actual pathfinding. So many times playing a local game, I'll click an area transition and it will start well before my dude finishes moving up to it.

Worse: When it picks the longer route around an obstacle. That happens way too often. I'm sorry. I know they are different games, but Age of Empires (1997) has a very similar map layout and they never had the same issues with pathfinding. Sure guys would randomly get stuck on nothing. But that was two in fifty. NWN there's just one guy, and they can't find a path down one level! Even WarCraft 2 the guys would at least get stuck on the trees in the exact direction you told them to go. I'd take that over 'Can't find a path to there' noise. Take two steps. Ooooh I can find it now.
Okay fine. AoE is a 2D map but NWN is 3D. Well again, WarCraft 3 (2002) very similar map layout and in 3D, no such range limits and never finds a longer path. Has body blocking. Can have hundreds of dudes finding paths all the way across the map. Maybe their pathfinding is a trade secret, but just knowing it's possible should be enough to figure something better out.