If 2 or more players are attacking the 3 same Skull world bosses they do not count towards the Challenge. You have to kill them solo. At first I was thinking that it was to do with Siptah vs Exile Land bug as when my friends and i were hunting them together on Siptah we were getting no progress but when i jumped onto an Exile toon it progressed. Then tested some more world bosses on Siptah with the friends again to find no progress so we jumped to Exiles and had the same problem until we tried to solo kill them when it would finally register the 1/5 World Boss kills.
Hello
Thank you for reporting this issue to us, but could you please use the given Bug Report Template?
This template has most of the information we need to start investigating and will make the process a lot quicker for everyone 
You can find it here: NEW Bug Report Template
Thanks in advance!
This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.