Over the weekend there were multiple instances where a group was created and converted to raid (first was Undermine raid on Normal), and the leader/creator of the raid entered, followed by others. Not one other person in the raid was in the same instance as the leader - who had to zone out and back in to join the rest of the group. Another instance was in a War Within mythic (not key) dungeon, where part of the party zoned in to one instance and the rest into another version of the same dungeon.