Might not be a bug, could just be my misunderstanding of the effects and I'm sorry I didn't save a log clip.

I sang vibrato in Comic repertoire and immediately after the song the paladin I was fighting communed word of recall before the next round of combat could ensue. He wasn't in champion's stand because I'd caught him moving towards me and slept him before the fight began.

I was under the impression that vibrato caused some lag but maybe that's limited to the Epic repertoire. So reporting it here in the off chance that it's a bug that there was zero lag.

Lag is not guaranteed, there is a saving throw.