API mob loot determination isn't working

Summary

Denizens mob loot determination isn't working, mcmonkey checked his part and says that it's MM issue.
https://github.com/DenizenScript/Depenizen/blob/master/src/main/java/com/denizenscript/depenizen/bukkit/events/mythicmobs/MythicMobsDeathEvent.java

Current behavior

For now if you're trying to modify mobs loot with denizen, noting happens, no errors, no warnings.