Still a little bug. Barrier seems to be on(Active) permanently, deactivating the barrier doesn’t work until you click the Activate barrier option first, even if it’s already up.
Edit: This also resets your choice when you leave/re-enter the hall, needing to go through 2-step to deactivate again.
Also, while adding decorations to the arena, if someone else is in there, obstacles and traps take effect on you, even though you are there as a non-combatant. While alone you are indomitable. Dunno if this is a bug or not. Seems like a bug.