I am playing on the patched released earlier, 0.7.0e, and running a Monolith instance (second one since patching). I had the objective to kill the Frost Wyrm, and cleared the zone before finding it. After killing the boss, my Quest changed to “Go to area and complete objective”, and there is no objective/quest marker on my map at all. I ran through the entire instance to make sure nothing respawned and I didn’t have a portal somewhere. So now I’m sitting in the instance about to manually TP out since I have no other option.
One thing to note is that I had my Quest log minimized at the time of the boss kill. The attached screenshot is after I restored it.