Started the quest this morning (GMT) and hardly any Marching Dead spawned (I'd say about 6 in total)
The Marching Dead Guard also didn't spawn meaning the quest couldn't be finished. Might be a lag issue, though!
Happened a couple of times with me.
This is an inconsistent issue that involves not all encounters properly reseting, but oddly appears to affect the Marching Dead quest far more than others. If anyone can think of any incidents where this has happened on other quests, please mention it.
The Big Rat quest has issues spawning the big rat now and then Ive noticed.
A possible fix has been implemented. Please report if this happens again.
This isn't the same issue but several times during the Cleaning the Lavatory quest in the new arrivals tower and Goblin trash blob in the gobsquat. I have had the creatures not spawn, not because the spawn hasn't reset but because my character hasn't triggered the spawn. Upon moving back to the entrance/near the descending ladder creatures have spawned, they just need bigger encounter triggers.
This may be what's happening with some of these other bugs as well!