Went to a Tier 2 Clear quest at Bell Lake. The quest marker was visible on my compass but did not appear in the area of grass that it should have. From several meters away, you would see a bouncing quest marker that looked like it was underground, but once you got close it would disappear. Moving around and looking at the "Distance to the marker", the closest I could get was 6.2 meters. I finally decided to just try digging down at that point, and sure enough, I discovered the quest marker 5m below ground. When I clicked it, I teleported to ground level, the hole I just dug was no longer there, and no zombies spawned at all, so I had to quit the quest.