Lachlann not turning red during unblockable attack

Lachlann of Endless Lament has an unblockable attack that he uses at the start of the fight, but he doesn't turn red to indicate he is casting an unblockable ability. He uses the voice line "My rage burns" and then swings his fist in front and behind him. Neither of these hits are blockable with a shield. The majority of his moves are blockable but this one isn't as far as I can tell. I've tried for the last 15 minutes to block it and it doesn't work. Please update this animation to include the red pulse.