So i basically killed the rose garden boss and the npc didn't summon so i couldn't finish the quest and enter the bon map.
this procs sometimes for me too, best way to prevent it atm is never let it die at the left most possible spot. Unfortunately its been a bug for a while
Bumping as this is still not fixed, Killed him today on BS, left side (not pinned, just regular TPs) and npc didnt spawn. Suprised that theres no other way to code this; i.e. npc is always there, and when the boss is killed he can drop the bouqet, and you need the bouqet to proceed to the next stage (similar to previous stages).