We adjusted the statistics of the transports to make picking up and dropping off units more reliable (on the average map). Units inherit the velocity of the transport as they are detached when dropping them off. If the transport lands too fast (lift factor) then the units can fly off quite a distance (1 to 3 land factories far). If they end up in a mountain, a large field rock, a structure or some other unpathable bit of terrain then they are destroyed upon contact with the terrain. That is why the lift factor is quite a bit lower than before - it almost guarantees that the transport is only moving vertically upon dropping.
That's the problem , as always: I'm open to a (different) reliable fix to both (reliable landing and quicker lift off) problems. But I'm not going to spent time on it when the current solution only impacts maps that look like this: