I've killed the kwama group boss in Forgotten Crypts by myself several times, but the daily endeavor still remains uncleared.
For some reason, ZOS started using the term "group boss" recently (the last year or so? Not sure) to refer to world bosses, a poor choice in my opinion, because it sounds like they're referring to public dungeon group bosses.
RealLoveBVB wrote: »If you hover over the endeavor, it will give a hint what to do exactly. They are mentioning the "bosses visible on the world map" when it comes to "kill a group boss".