I had a full group in Frontier Uppland zone farming Wintery Dirge/Auroras, highest lvl being me at 34. They con'd Red/Purple and would not give us Task Credit for any task. We did a test where one of us left the group and task worked just fine. Only seems to be a problem with a full group. Ended up sitting out on my shaman and leaving them buffed so they could at least get task credit.