Lv 62 shaman here, doin the escort for khadgar’s pet.
I immediately marked the familiar and followed it around, and waited until he said “khadgar is waiting for you” or w/e.
Quest cannot be completed however? I’ve been waiting/talking with Khadgar for over 5 mins. And no, the quest didn’t fail, and I never let the familiar get out of range.
I completed it fine today, jsut wait uptop with the guy until you see khadgars question mark go yellow for hand in.
Thanks for responding… And yes, after I abandoned then I waited up top forever and it completed.
I still don’t believe it’s actually functioning 100% correctly.
I did it twice. Once when Shat was bangin’ and everyone was doing that quest (marked mine with a raid icon) and again on my druid yesterday. No issues either time.
I’m having the same problem. Definitely bugged, just not for everyone. Completed it fine on my alt. This time around, the assistant finishes the tour, says “Khadgar is ready to see you now” and the question mark over Khadgar is grayed out.
Did you follow the right servant? I screwed thst up once years ago by losing track of the servant.
Yea, I have also learned that lesson that you speak of.
Nowadays I immediately mark any patrol (including the khadgar one) with the Orange circle.
So yea, what I seem to have discovered is that you must actually sit on the balcony above with the familiar, until the DBM timer finishes and the quest marks complete in the center of your screen. 
Confirmed - you can just sit on the balcony next to G’eras and wait for the quest to complete - you don’t need to follow the servant all around Shattrath but standing next to Khadgar will not result in a complete