Astos

Hello, I'm experiencing a bug with the Changing of the Guard quest. I've received the quest to assasinate Wenfeld in Crucible Keep. After I assasinate him, however, it is not giving me any option I can see to leave the Dozens Token at the Alter. The alter is grey, probably because I clicked on it on a previous visit to Crucible Keep (before receiving the quest). Am I missing something? Thanks, Astos