Empty Cathedral Rooftop after first Kitava (no Lily)

Context:
1) Expedition, trade league, softcore
2) Party of two
3) Both at the same quest state, The Ravenous God: Use the Sign of Purity to defeat Kitava.

Steps:
1) We enter Kitava's "arena" in Cathedral Rooftop area, he goes to half his life.
2) I try and see if I can avoid the death cinematic, I portal, I use the portal AFTER he emerges for the last time, and before he kills us, and I go to Overseer's Tower.
3) I try to go back to Kitava's arena through the portal, it says I cannot because it's not safe.
4) I try to teleport on my party member. It works I go back to Kitava's arena. He's all red and angry, but not moving. The quest state hasn't progressed. I can't go in / out from Kitava's arena. I try to access the other side (I forgot how, now, because I didn't realize I should have taken screenshots and payed attention), and I can be on the other side, but not go in the arena from the other side.
5) My party member creates a new instance for the Cathedral Rooftop, I tp on them, they can see Lily, I cannot, it's all empty.
6) When I try to go back to the instance with Angry Red Kitava through ctrl click on waypoint, it say I can't join the instance through this method.

Why I think it is a bug: Because I would have imagined that the game doesn't let me be such an idiot that I have to do Kitava all over again :(

Images: I don't think there is something specific enough to justify the bother of uploading, but I took screenshots after I got to the empty CR without Lily, and can provide if you want.