I just unlocked the Ghosts of the Deep title, but it's not counting towards my guardian rank challenge. For rank 10, you have to get 5 titles. I have four currently, but it's only showing 3/5. I have the titles for the Dawning, Guardian Games, Spire of the Watcher, and Ghosts of the Deep.
-
Bungie are aware - Ghoul has been bugged for GR since it was added, you'll need to do another one instead of it.