Guild Wars 2

There is a bug in the Hero Challenge: Defeat Matriarch Scrabclaw. The challenge is located in Tanglerot Hills which is in Fields of Ruin. I and other players just tried it a few minutes ago. I was not in a group with them. They were just other players.

When you interact with the challenge dialogue comes up with the words, “Scratched into the rocks at the base of the roost are the words”Scrabclaw challenges all.""
There is only one answer saying, “I’ve already won that challenge.”

After clicking the answer nothing happens besides the panel on the right with the progress bar pops up but no challenge.