Bug with boss achievement

lokm

Hi, here to repport a bug i got after kill the boss (last before final boss i guess). The boss is the one with 2 fighters who use sword and mark with red spot on map. After kill them, got the achievement, got the white light told me reach lvl 20 pvp to beat them lvl 2 and the sword reward but when i go to the last boss door and look map on altar, it's like i've not kill them. i'm not the only one with this bug, same issue on steam discution : http://steamcommunity.com/app/473690/discussions/0/1473095960825487130/

Hope this could be fix, cauz i can't continue the pve story for now.