Arch Lich has not spawned when Rhag 2 was killed now 3 times in a row in the instance on Aradune. We cleared traps, killed rhag 1, cleared more traps, killed rhag 2, and no arch lich spawn. We have heard of other guilds having the same issue.
We had this issue on Rizlona the first time we did Ssra. The second time it spawned. Hopefully they fix this issue.