Multiplayer - legacy of the vaal quest failed

Bug Report ID: #677121415

Played the Legacy of the vaal quest with a friend in a party
Friend talked to alva and the platform was raised after boss kill. I did not stand on the platform but right at the edge.
I got stuck in the "talk to alva" part of the quest and on the boss platform after boss kill. Could not move my character at all or even pick up items. Made a portal that could take me to the city. Alva is there but could not speak to her. It told me to go back to the temple and speak to alva but she is not there.

I had to start a new instance and redo the boss.

Can confirm with what OP reported, i'm the friend who played with them.