If you Have Leokk at the field, he Blocks the Quest progress in any way.
Means:
if you play a 3 Attack beast while Leokk is one the field it Boost the attack to 4 so it dont count for the Quest
BUT
at the same time if you play a 2 attack Beast while Leokk is one the field, it getting boostet to 3 Attack but it also dosent count and give no progress to the Hunter quest
so… that make no Sense