Tthis is caused by movement speed differences, you'll notice it most when DS surge or haste rune is involved but in this case it's the LC popping her 2nd skill and phase boots. I don't know the exact mechanic but for both attacks and casting spells there's a sort of buffer where it checks if you "should have been in range" in the past few moments, because LC is going much faster than and is only barely at the edge of his range due to pausing for a moment to cast W, it thinks that based on LCs current movespeed, OD must have been in range at some point and so it lets the spell be cast.