I'm having a similar problem, but reloading, waiting, turning away and turning back (which did make some people appear) doesnt work on my Cassandra or Blackwall. Since i hit Skyhold, neither of them appear. I've wandered around trying to find them, since i know sometimes characters wander. I had the issue with Cassandra a few times in Haven, but i've been in Skyhold for hours and she only appears at the War Table. Unless Blackwall buried himself in the barn, hes never there either. Ugh.
Otherwise, everythings cool.
