Can confirm; all blazes in the vicinity aggro if you hit one, even if the one you hit doesn't have a direct line of sight at the player.
After experimenting with it, it seems it works much like pigmen aggro; as in, this bug won't occur if you kill the targeted blaze in one hit.
Hope this gets fixed soon.
Fernando Manuel Cárdenas Segura
Can confirm; all blazes in the vicinity aggro if you hit one, even if the one you hit doesn't have a direct line of sight at the player.
After experimenting with it, it seems it works much like pigmen aggro; as in, this bug won't occur if you kill the targeted blaze in one hit.
Hope this gets fixed soon.