Had this happen twice today:
A) Other player and I step on the elevator, activating it.
B) Someone else joins the lobby before it goes down, leaving the elevator stuck.
C) After a minute or so of waiting, the joiner quits the party and the elevator goes down.
Everyone still in the party loses 10 mist and gets stuck on a black screen. It used to be that the elevator would go down on its own after 20-30 seconds, and things would progress normally from there.
http://u.to/RjoPAg Proof.