Not sure if this happened in today’s patch, but I just tried to do the Arah personal story step “Victory or Death” with a friend, and neither of us could interact with the cannons in the use the reflector cannons to combat the risen giants phase.
My friend is a mesmer so we put down some mesmer reflects that seemed to reflect the projectiles but we eventually gave up because the risen giants never went away.
Same here. Nothing works not even the repair anvil.