Clearcasting not procing from Arcane Missiles

Maybe I remember wrong, but I'm pretty sure AM ticks/waves used to proc clearcasting. I'm fairly sure I remember the the clearcasting icon "sometimes" popping up around the 3rd missile so it can't be lag or confusion on what proced it. Well I noticed today that I never got it to proc other than very rarely with the initial cast.

Now before you jump on me about "on spell cast" and "on spell hit" read the description from the talent:
"Gives you a 2n% chance of entering a Clearcasting state after any damage spell hits a target. The Clearcasting state reduces the mana cost of your next damage spell by 100%."

My Mark of Defiance says on spell hit and works fine (other than a hidden cooldown) with AM like it used to.
Why the hell did they stealth nerf AM so much? It's getting impossible to justify staying arcane. I'll just use invis every boss fight (that needs threat management) and wait for my RF tanks to get better (gear) and go easy on the trash in between. Who cares about trash anyway?