So, as the title says, me my mum & my aunts went into the undercity to kill alia so we can progress the story. I got progress despite not being the one that initiated the instance but the one who did one of my aunts & the rest of the girls didnt. And they still arent, even in their own game worlds. Is this quest bugged? Or is there something to this we dont know about?
Any help is tremendously appreciated! 
Same problem here.
I ran with a friend in his game. He got the quest completion and I didn’t.
Next day we ran the Alia quest again in my game and I get it this time.
Then we run another quest in that dungeon, still in my game where I activate the portal to the undercity and once again, he gets the quest completion and I do not.
Playing with friends does not appear to have been test consideration.
Update: Defeat Yoche is the name of the second quest.
Yeah it bugged for my other half as well and she has run it 6 times now and it will not complete so she is now locked out of a needed core gameplay activity. This is not a little oops this is a huge mess up on blizzards behalf, a multiplayer game where it bugs if you play it multiplayer 
I too have this issue 
my friend got credit but I did not (and we ran it twice in a row). I was the party leader and initiated the instance both times… I’m gonna try it solo and see if that helps. It feels really awful to be stuck locked out of something so crucial.
Edit: Returning alone about 24 hrs later worked! Dunno if it was a bug fix but definitely give it another shot alone in a new session.
have same problem, I run it 3 times now and still cant progress, my friend finish quest, I cant
Just hopping on the bug train. Just ran it twice with my husband and it’s not progressing for me but worked for him.
Party leader gets it. Just switch party leader. It just had it happened to me switch leader and got it.
happen to me just now, i am the party leader, p2 started it first time, got credit, i did not. i started the 2nd, still no credit
edit: kicked p2 outta the party, ran it solo and it completed
Make sure you do t pass party leader. Leave and have them join yours
Had the same problem. it worked the second try but my wife has had no luck. its a glitch
Hello, my wife has the same problem. We tried for 5 times, no luck. I hate it!
Same here. This is ridiculous. Being locked out of a necessary core activity is insane.
We had the same problem. What worked for us: The quest completion only counts for the one who had the final hit and thus “really” killed the boss. That’s why we always had to go in twice.
Thanks! Can confirm this worked for us as well.
Same problem here, doing undercity alone so always doing the last hit but no completation (not for me but my gf)…
had to solo it for credit.
Same problem here. I’m the party leader, and the other player is the only one getting credit. Making sure the other player backed off so I got the killing blow on the second run may have worked since I did get it on the second run. This has happened in both wings that we’ve done so far.
same here. only way to progress is to solo it or as suggested be the last one to hit the boss. still have to do it twice or more to progress the group. Really breaks the multiplayer experience. Blizzard, it’s been a week now. any comment? any?
Still bugged. Ran solo and did not get quest completion.
Yep, still bugged. Did get all the quests for this done, but had to run each one twice in a party of two, taking turns doing the killing blow.