Journal Quest Log

[IanB]

I was/am getting annoyed seeing ! on my in-game map, going there, not finding a quest, so I installed Journal Quest Log and its Lib, looked like exactly what I needed, but I have a problem.
Let's take quest "To Altaire Castle" in Stormhaven as an example, on my map this shows up as a ! and the addon says it is not completed but when I go there I cannot find any quest-giver. So I look in the Wiki, this shows the predecessor quest as "False Accusations", this quest does NOT show on my map and the addon shows it as completed. So I look in the Wiki for the follow-up quest, this is shown as "Army at the Gates", again this does not show as a ! and is shown in the addon as completed.

How is this possible? How can the predecessor be complete, the follow-up be complete, but this quest not complete and no quest-giver available?