>>546267230
if it's example. shadowmourne, your ICC lockout will be lifted until you have all the shards. If the quest won't become available til tomorrow like the egg in BFA Uldum, it becomes available immediately.

if a quest mob has been known to have a 20 min spawn timer since cata, it will stay like that. if there are wowhead posts from legion-TWW saying its been bugged and unfixed for years, blizz will hotfix it for you.