Converted Drowned not spawning with Trident or dropping Trident

Zombie spawner converted into a trap to change zombies into drowned. No drowned are spawning with tridents. After I kill them, no tridents are dropping at all. Gold and Zombie flesh are the only other drops. 

I have killed maybe 1000 +/-. I have 7 full stacks of zombie flesh, 14 gold and no tridents.