Trading

So, I figured out how to set up a trade with an NPC ship, my half of the trade is loaded into the airlock, but nothing ever happens beyond that. Shuttle doesn't pick up/transfer supplies. NPC often ends up jumping out without the trade ever completing. Am I supposed to do something specific, or is this a bug?

It should happen automatically, just set up the trade then wait. Sometimes the crew of the trade ship can be a bit slow in loading their side of the deal.

Some kind of countdown timer would be good to let you know how long you have to trade.