The quest - Putting A Plan Together is currently bugged. The quest requires you to return three Centurion Parts. Two of the parts can be returned without problem. However, the third piece inside the cave can’t be returned, and therefore the quest cannot be completed.
Joining a different shard, re-logging, /reloading did not fix the issue. The quest is bugged, and the Necrolord Assault is unable to be completed.
Same with me. I cannot turn in the piece from the cave. Please fix!
I was only able to drop off one part. I’m carrying around two… don’t understand.
I was only able to return the piece from the cave and cannot return either of the other two.
People are progressing too quickly through the content… they have to find some way to slow us down from getting legendaries. The really sad thing is… this was bugged NUMEROUS TIMES in test 
Glad those bug reports were read and addressed
a mi tampoco me permite entregar la mision :c
Has blizzard got back with y’all, I’m having the same problem.
+1
welp me too
Having the same problem. Tried abandoning quests, leaving zone, logging out/back in, disabling all addons, joining a group, dropping a group…a lot of things and nothing helped. Can’t turn in the 3rd piece - the one from the big cave is the one I am having trouble with.
Oddly enough it worked for the first 4 characters I tried it on but now the 5th character is stuck and can’t complete it.
I really don’t get it. There are what? Maybe 20 new quests in total across the 4 covenant assaults? This one has like 6 quests (and 1 of them is a nothing bread crumb quest) and 3 of them are bugged or broken in some way…
I wasn’t even OFFERED this quest on Wyrmrest Accord.
Come on, Blizzard. You’re wasting our time.
It appears to be a possible server-related issue? I was able to return the third piece by joining a group using LFG and basically shard hopping.
Note: The group was a party and not a raid. I ended up completing the quest while in a different shard and still in the party.
Note2: I joined several groups and I was unsuccessful at first, but eventually the quest objective ticked and the piece was registered once I joined a new shard.
Note3: The quest is still most definitely bugged.
Good luck everyone. No other update from me.
Can’t turn in a single piece now. Lots of toons just standing around trying to get the pieces to drop.
i had no problem picking up the part in the cave and turning it it. did nothing special. the part that was buggy for me was the slime eating 8 mob took for ever to get credit
I could only turn in one part. Can’t complete the assault and get credit. This is stupid.
+1
help me
Also having this problem. Any word from blizzard yet?
Can’t get that third piece turned in either… (sigh)
Same here. Cannot turn in the last part.
Same for me. I can’t return the third piece. It appears it’s a random piece that can’t be returned, as mine isn’t the one from the cave.