I had exactly the same thing happening. No problem in the end, but the questlog is still saying that (although he's clearly in the camp). For me it happened, because I forgot make the weapon in act 1 and just wanted to get that quest out of my quest log. In a similar way if you recruit Minthara, and didn't do any of the stuff before the Shadowlands (which in my case was the Underdark part for that playthrough), she will also not go along.
I find that pretty bad. Even if it makes sense from a RPG POV, it would be great if you could bring the non-origin characters back to those areas too. Even if nothing much happens there with them.
