Character Stuck - Boss Bug – Gorian, the Moving Earth (T5 Map)

I encountered a critical bug during an Endgame T5 map while fighting the boss Gorian, the Moving Earth.

When the boss was at approximately 25% health, it became completely unresponsive. The boss stopped moving, appears to have lost its hitbox, and cannot be damaged or interacted with in any way.

Additionally:

I am unable to leave the boss arena.

I cannot create a portal to my hideout from inside the room.

Restarting the game or returning to the login screen does not fix the issue, the instance remains in the same broken state upon re-entry

This effectively leaves my character stuck in the encounter with no way to progress or exit.

Video Evidence: https://www.youtube.com/watch?v=9m8DvNVpDwo
Account Name: Jacow
League: Runes of Aldur

Please let me know if you need any additional information.

Thank you in advance for your assistance.