ALL Mobs don't drop loot

The title says it all, EVERY SINGLE MOB DOESN'T HAVE LOOT DROP WHEN KILLED!!!! Even the Caves and Cliffs ones!!!! On both game modes too.

Steps to reproduce:
1. Spawn any mob or find one
2. Kill the mob and notice how they don't drop loot they just drop xp

Expected results:
The mob should drop their respective loot

Actual results:
The mob dies and their loot doesn't show