At the level of pig marsh, in the orchard, I've tried no less than 5 times to guide pigs to go to the lifter, but they always stuck on the right upward side even if the lifter was down.
And once a pig had finally dropped, but immediately run to the fruit tree upside and then cross through the geometry molds and go back to the upside path.
That's what locked me to play the game smoothly!