The King in the Mists Progression Bug - Boss Becomes Unresponsive

Here's the current situation:
After progressing through the first phase of The King in the Mists by reducing the boss's health to a certain threshold, I transition to the maze map. Upon finding and entering the portal that leads back to The King in the Mists from the maze map, the boss becomes completely unresponsive and takes no actions whatsoever.
The boss does not progress through any phases and remains stationary. Additionally, climbing onto the surrounding totems is blocked, making it impossible to continue the encounter.


Below is a video I recorded myself.
https://youtu.be/3Ncgxt-Dn3Q?feature=shared

Same for me, any solutions?