Diamora stuck in phase 1

After running into bug where Diamora just vanished during phase 1, I relogged with the same character (Lvl 52 Infernalist Skeleton Summoner) to repeat the fight. After changing the skeleton setup, went for her.
She got hit hard, went into water, jumped over the ring twice and returned. Got hit hard again, tried to get back to water and then stuck, got frozen multiple times, got killed without any further actions from her side.
Bug Report ID: #2771125227