Guild Wars 2

I gathered all letters and finished the achievement, yet the item still says “(Incomplete)”.

I have that, too. The 21st letter is missing if you read through them, but I also got the achievement.

Same here. Achievement is complete, all 21 letters found, but the journal item remains incomplete

Noticed the same thing. Did some checking:
- There are only 20 letters.
- The 21st item in the collection is the book collecting the letters (“Caudecus’ Correspondence”) which you automatically get after reading the first letter and starting the achievement.

So the real bug is that the book we have upon completion of the achievement is still labeled “(Incomplete)”.