This achievement [Boss Hunter: Expert] does not appear to be crediting boss kills?
This is kind of frustrating as I’ve killed each of these bosses several times over… and it rewards the Wei card. Only card missing from that 7-set.
(Achievement location: Adventure → Normal → Towards bottom)
Try doing them in order. I was trying to resolve this issue as well by killing bosses over and over, but right now im doing them in an order and started getting progression. Try killing Batuark next if you maybe didnt.