I'm pretty sure that transition API never worked properly. What I always would do is make 2 transitions with one having a slight delay like so:
transition.to(newDot, {time=80,y = newDot.destination_y - 50})
transition.to(newDot, {delay=80, time=40, y=newDot.destination_y})
Just work with something like that so just change up the numbers to your liking. Hope this helps.