Black Fox Flag missing

I got a collectible, used it, but it is still showing as incomplete in my adventures tome.

The item is Black Fox Flag, which I should have, because I have whole East Luterra region done and it is suppose to drop from Alifer boss in the Glorious Wall quest.

It seems I can’t repeat the quest, nor I have the flag.

Is this a bug?
How should I proceed?

  1. List item

uld I get to the collectible?