Title explains the issue, really. it's not just visual either. The Unstoppable icon doesn't light up on the character sheet or appear in-game by the weapon icon (bottom-left), and it didn't Stun champions in the nightfall. Everything seems fine on other exotics and legendaries, although i didn't test all of them. My guess is that it's cuz it also jolts/overloads with an ionic trace, so something's not letting it double up.