I submitted a report for this bug using the in game tool but am also posting it here when I realized I had left out a few details. Fighting Champion enemies you typically get a champion tagged piece of equipment (sealed enchantment), the type of equipment varies based on the type of champion. The bug is area specific. When you fight and kill a Champion in the Lotus Halls you don’t get the expected item, in fact you often get no more than a single drop with no special tag.