I ran Haunted Refuge four times, on difficulty 2 and 3 a few minutes ago and Slay the Festering Shambler just doesn’t come up. With this bug, it is not possible to finish finishing the dungeon. What do I do?
There’s a similar complaint for bugs on consoles: Festering Shambler not populating in Haunted Refuge
Same. I ran it twice on WT2, exited the Diablo app entirely for a few hours, came back and ran it again, and no Shambler spawn. Unable to unlock Brawler aspect due to this bug.
Just posting to say same issue, for visibility.
experiencing the same issue
I have the same problem here
Currently have the same problem, restarting the dungeons does not help.
Same issue here. Needs to be fixed asap as the Brawler aspect feels real good for some builds…
same, reset it 3 times. no boss.
No boss…reset dungeon…no boss. No aspect given!!!
Got the same problem
Im in the same problem crazy it hasnt ben fixed yet considering the ammount of money you are fetching from this game you dont have the quality level to fix issues within a day. your a very disgraceful company fix your games.
Same issue, tried it 3 times with no luck
Having the same issue.
Ran dungeon twice never spawned 
Same thing happened to me
Ditto also happening here.
Running into the same issue reset twice no change, no spawn, just adding to this to keep it all informed.
Same issue here. World Tier 2, had it twice and the Festering Shambler does not spawn.
Same issue here. World Tier 2
Same here, although had this happen in the Haunted Refuge, was supposed to kill the Festering Shambler, he/she never showed up.