Once she does her big AoE attack, every character will freeze on the spot and not be able to move, or attack unless facing the boss directly. This should be easily replicable to see the bug.
I had this happen too on PS4 NA. Nothing you do except closing out the game and opening it up again will fix it. I had it happen both times I played this dungeon over the weekend. /reloadui and “get me unstuck” also doesn’t fix it.
The only way we could remove the bug was by dying. Thankfully we had a necro to rez ult us. But even the person who used /stuck got brought to the beginning, still stuck. Thanks for verifying the bug.