I took my pally up to Ravenholdt Manor to hand in Heavy Junkboxes for Ravenholdt reputation. He is revered, 6644/21000. Other people in the room could see the blue quest marker, but I couldn’t.
I tried logging out and back in again but to no avail. I had just taken a trip from Stormwind up to the Arathi area and flown from there to Ravenholdt Manor so had not been questing in the area.
I don’t quite know what the solution is - is it a reportable bug or what?
Oh and Pally is level 80 and has the other Insane in the Membrane reps.
UPDATE: PROBLEM SOLVED. Paladin had Lorewalking turned on. As soon as it was switched off he was phased back to Dornogal and had to do the trip all over again. On arriving at the destination after the second trip the blue question mark was there.