I also have two Leopard 2014 males that wont breed. I've tried switching between multiple females, taking them for an hour car ride (which just stressed them), rubbing a sperm plug on the female, exchanging male sheds, keeping the males together for a short time, cooling, putting the female into the males enclosure and vice-versa, uhh yeah, not sure what else to try. I don't think they're "ninja locking" as every time I check the male is far from the female and has no interest.