An issue wherein the description for the summoner skill Dreadwyrm Trance did not indicate that an effect must be inflicted in order to receive an Aetherial Attunement stack.
So nice of them to tell us five months later, although every SMN figured it out the first time they tried to squeeze in one more Fester on the last boss in Neverreap and it went immune and you didn't get your stack and messed the whole rotation up.