Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

Could someone explain to me how the Dissonant Chord's Break Concentration Feat is supposed to work and if it actually works? Last night I tried to test this newly gained feat and I just couldn't see it do anything. I tried it passive (sneaked next to a spellcaster that was casting spells on another PC - no effect), then tried it "active", means, I set another player to hostile and he cast spells while my Dissonant chord attacked him in melee. I never saw any concentration checks in both scenarios and apparently did not interrupt anyone's spellcasting. Am I doing it wrong or have wrong expectations?

I also have a Dissonant Chord(Level 21, with 4 levels invested in the class), and I've never seen anything in the combat logs to indicate the break concentration is doing anything.

Break concentration applies a penalty to concentration skill on all enemies around the dissonant chord, past that point you still have to deal damage to them in order for the spells to fail. And if there's no feedback it's because I removed it as I thought it was spammy and useless >_>