Doryani not Phase Transitioning, Waystone Drop Chance Bugged

I've lost count of how many times I've died to Doryani (and lost the citadel) because he wasn't transitioning to his final form. I don't know what causes it, but about half the time he simply becomes immune to damage and continues spamming his attacks when brought to ~40% HP in his mage form.

Secondly: Waystone drop chance seems to be bugged. I've done two dozen citadels in the past two weeks and have NEVER gotten more than one fragment, despite running with 120% waystone chance on the map + 60% from towers.