Are you using both the trap and the repellent? You can only get the comatose lizard by using the trap without the repellent. It does mean there's a chance you will lose out on the item.

It'ld be better if someone else can confirm it, but iirc you need to only have the Lizard Minion Trap in your inventory, but not the Lizard Minion Repellent, and meet the lizard RE and successfully capture the lizard