Incarnation of Dread - Invulnerability Phase Bug

Was doing Incarnation of Dread with a buddy, during the last invuln phase the boss didn't stop his channeling after collecting roses and bringing them to him. Collected roses twice, since we then both died, but still didn't end the phase. At some point it told to me collect the roses again, but no roses appeared in the arena.
https://imgur.com/a/j6ausaM