The White-lipped tamarins in Worlds Apart seem to have been moved from their enclosure near the exit to the first primate enclosure you encounter where the Goeldi's pair were first kept after their arrival.
I believe that this was, on my last visit, still the enclosure for the second pair of golden-headed lion tamarins. Not sure what this means for the lion tamarins, although I must note that they are probably the shiest members of their species I have ever encountered.
Since they arrived I have never seen them outside at all (in fact, every time I have been to the zoo they have been in the exact same place - sitting on top of their indoor nest box, only visible by looking through the access chute between their indoor and outdoor enclosure).