May not be a bug but an intensional change which isn’t listed in the change log.
Since the new patch Lucios Dance Party emote music is tied to the game music volume in game. But this is does not effect any of his other emotes such as Capoeira or in the groove. Also the start of the Emote SFX still play just no music, so the sudden stop of the audio makes the emote feel out of place.
Ok those other two are much shorter and naturally quieter. But as someone who is used to having game music either off or low it made me think that the emote was completely busted to start with. If its an intensional change then you might want to also change the intro SFX to the emote to also be tied to the music volume.
Demo Vid: Lucio Emote Bug or Change? - YouTube