You just dredged up a deep memory. Is this the thing where the enemies would keep going up and down a ladder just generally speaking? I don’t know if I ever made it to level 29, my memory is not that good lol, but I do have memories of enemies just constantly going up and down ladders occasionally.
An enemy will try to reach the same floor height as the player, and if it can't it will prefer climbing up over climbing down. It also looks left then right for another ladder or free-fall that might bring it closer to the player's height.
In the case of level 29[1], the best position on the second ladder is to move to the top then use the horizontal pole to move left. That's what it will do when below the right-side pole. But when it gets above that it switches to thinking it should move down. Because the goal changes it gets stuck in the loop of moving up then moving down.
What you may be thinking of is when the "best" position is at the top of a ladder but no clear path left or right. It will climb to the top so the only way to go next is down. But after moving down immediately wants to go up again.
