Just went and checked, and it worked fine for me on PC/NA.
You sure you cleared all the adds from all three portals? I've had them get stuck inside rocks on occasion, and afaik if any are left alive the boss simply won't arrive.
Perhaps it's a bugged instance? Sometimes logging in/out quickly just puts you back in the same instance you left; which is usually fine if the problem is on your PC or UI, but not if that particular instance is borked somehow.
My only other guess is to ask a guildie or someone to go there, verify it's working for them, and port to them. It only takes about 90 seconds, since you can use your mount in that PD (which is why I checked on my end) ;p
Good luck!