Ah, I hadn't thought of trying it in an unpatched game. I had checked some walkthroughs, because I kept losing the mission, and those didn't mention anything about the transport heading back so I assumed it was a new thing.

You're right that landing when the transport is close wins the mission, but I must've waited too long for the transport to get closer that by the time I landed, it had moved out of range again and the mission was considered a loss.

Regarding the ace, that must've been a fluke then even though I replayed the mission a few times. When trying it again just now the ace did show up at about 23km away from the Tiger's Claw, but only if I'm there. The transport itself doesn't trigger it. I think I stuck close to the transport all the way to the Tiger's Claw previously but maybe I stepped just outside of the trigger area at one point? Who knows :)

Thanks for looking into it, and sorry for not double checking with the original game first.