I'd been hunting Hive Overseer on Hive for days and this don't loot anything but gold and kollos shell. By the way, they don't respawn if u stay on the chamber but the wiki says that is not possible to block their respawn.
Can you please look if that is working?
I think you don't want them to drop Hive Bow easy, but its a shame that easier creatures like spidris, kollos or waspoid give much more loot.
Wikia Page: https://www.tibiawiki.com.br/Hive_Overseer