I've done all base 1, 2, 3, and 4 quests so far and found nothing new. Been pretty thorough checking optionals, known chest locations, and all the nooks & crannies incase they added a new chest (like the Feywild unicorn chest). Now that I'm on base 5's I've changed tactics to only do "heroic only" quests. Have done all but necro 1 stuff so far with no chests (any quests with epic/legendary versions not checked). I'm only human so it's possible something could slip thru the cracks of checking but I likely covered all the quests well.