In true mode, the homing lasting concentrated light + gridlike ethereal lances attack, the bottom to up lance fail to spawn if it is placed below the player world border. It is quite possible that it applies to other lance attacks as well, or it might be that it applies to the west/east ocean world borders as well, though that will require further testing. It does make the attack somewhat easier to dodge as you get more room to reposition the concentrated lights (though that doesnt really matter if you've mastered it already).

I'll post more updates if I can get more testing done.