I looked everywhere else for the solution to this issue, Google, Gamefaqs, this forum, ect... And only found one other topic that mentions this problem without any ways of fixing it.

A group and I started playing Icewind Dale 2 online recently, we used GameRanger to connect and everything has been going fine. Eventually important quest NPCs started disappearing and we could not longer progress through quests. We made a new game after we couldn't figure out what the problem was, but when we got a little further, people like Olap and other quest NPCs started disappearing again.

I am the host of the game, the game is updated to version 2.01. At one point I even attempted to use the tweak pack to see if could fix things the patch did not. I tried clearing the cache, rebooting the computer, saving and loading in different slots, trying the auto save, uninstalled and reinstalling, following the guide about how to correctly install this game in Windows 7 OS, and many other things.

Operating System: Windows 7
RAM: 4 GB
Patch version of game: 2.01
I do have custom portraits and sound files in.
Using Game Ranger
5 Player team, soon to be 6
If there is any other information you need from me, feel free to ask me.

I really do not know what to do, if anyone can come up with the solution to this problem, I would appreciate it very much so.

I don't have an answer, but all I can say is that I'm also experiencing this problem.

Operating System: Windows XP Pro SP3 under Boot Camp on a Mac
RAM: 2 GB
Patch version of game: 2.01
Playing multiplayer via in-game TCP/IP connections

Any suggestions?

Same here. Just started playing IWD2 with three of us connected to multiplayer via local lan over TCP/IP. Isherwood in Palisades is first NPC that is completely gone. Cannot continue the game without completing this quest.

anyone make any progress on this?

Same issue. Three of us connected TCP/IP via GameRanger, all using the GoG version (2.01) of the game. Multiple NPCs gone missing at the Targos Docks and cannot advance many quests/side quests.

Anyone have a solution for this yet?

At one point or another a vital NPC disappears. Very annoying, cause it is a long game and sooner or later it's bound to happen.

My friends and I have been using an extremely annoying workaround. We export our characters and start a new game, then use the cheat to jump to the chapter we were in when the NPC disappeared. You have to play the chapter all over again. D: Happened 3 times and on the third one we just kinda lost interest in the game.