I’ve killed Cairn the Queenslayer three times in the past week during defense of New Loamhurst, and none of those times did I receive the Daily Bosses chest. People in map chat who killed it with me said the same thing, that they didn’t receive the chest and hadn’t completed the daily.
Daily Lake Doric Bosses = “destroy one of the legendary bosses patrolling Doric’s Landing” (Immelhoof, Agatha, Queenslayer)
Does not say it has to be in a recapture, only that you have to destroy it.
Definitely a bug that needs fixing. I submitted bug reports with screenshots each time. Please fix.