Ok, watching the goings-on using planes on patrol I've observed an enemy transport simply disappear... so I'm assuming that it was sunk. I guess I was just having a no good very bad unlucky day with mines and transports around the city, but if a mine acts like an infantry against a transport the odds of what happened to me had to be near 1,000 to 1. The battle report never showed anything.
On another note, a mine is supposed to have 2 "charges"... how do you know if/when a mine has been discharged? How do you check for something like this? I'm assuming that if/when a mine exhausts it's two charges it simply disappears... without notice.