so this is a bizzare bug that makes very little sense and that I've only seen on terra, so I suppose it could be something with the map somehow.
anyways, the bug:
ground based transports refuse to unload any unit in the bottom third of the map. they reinterpret the order as a stop command.
Tested in 0.75b2 with S44, SWS, and BA 5.8 (hover transport)
