I got the following issue:
I'm playing Arcane Mage and got 5/5 points in Missile Barrage talent, but when i got 4 stacks of Arcane Blast and want to use the Arcane Missiles spell I dont have the proc yet and that happens at least 1/3 times of the cases. The talent is 40% and this is not normal 100% and it not gear dependent, of couse, cause it's a talent. What is the problem?
Yea, I completely understand that, but it happens 1/3 of the attempts, man, which is not 12,96% and I had a few moments when had to make 9-10 AB in order to proc, which is absurd. I played arcane in many servers and this happens for the first time.
What you are saying is completely anecdotal. Feel free to prove me wrong though. A test where you do a large number of ABs in a row and later compare the procs/casts should give a very clear indication if there's anything off with the proc chance. I'd say 500 would be plenty.