This quest, which is central to acquiring Soul Ash, cannot be completed this week since none of the Torghasts required are available. It’s already enough of a chore having to run this on every alt to get legendaries, please hotfix this to make the quest either doable in TC or any wing.
Did six floors of a TC to find out it wasn’t available there 
The quests is not central to getting soul ash it’s a little bonus soul ash not central to it.
Also the quest can be done this week or any week. It’s from killing a boss on floor 6 for any layer any wing. There is not a specific wing needed. Can confirm this on wowhead with people listing basicly all wings as being done on. The missing ones are a safe bet to be just no one posted.
If you dint get a drop from a floor 6 boss your in the wrong fourm go to bug reports.
True-ish. It’ll take a hotfix to be able to do it this week. But it can be completed another week.
Wrong. Even the quest text says you can only get it from 3 wings, none of which are currently available. And the wowhead comments support not being able to do this in all wings.
A blue on the CS forums has said they plan on hotfixing this so that you can complete the quest in any wing.
https://us.forums.blizzard.com/en/wow/t/quest-let-the-trail-go-cold/856235/10