Elixirs

[Electrophiles]

There is always a logical explanation. And such I shall give you:
classy makes u only loot what u can use. hence if you're full dex bird, you'll only loot dex items, crafting gems, recipes and essences.
hence the drop table is essentially spliced into a much smaller amount, severely increasing your chance to loot essence.

this is the same logic for using classy looter in farming blade steels, recipes, alien mirage, starry, dragon vanity, etc.