Blaze rods only drop when killed by player. When a Blaze dies in water, killed by a wither rose, or shot by arrows from a dispenser, it will never drop Blaze rods. I don't know if it is a feature, but it is difficult to make an auto blaze farm if the player has to kill them.
REALMS-8534
Blaze rods not dropping
Resolved
Works As Intended
0
Blaze rods will only dropped if killed by the player, (or a tamed wolf).
However, you may be able to use a trident killer to get the player-kill drops.
Before reporting bugs with mob drop conditions, you might want to ask about it on the Mojira Discord to make sure it really is a bug.