hmm that has something to do with rng
you sure at that time your mystic wasn't dead? or if you run with priest es was up same for endu debuffs?
you can run full crit if you want (like around 600 crit at IoD) and still get white dmg, that's why it's a crit chance
well it always does crit on IoD bams when its a hit from the back, and even in dungeons it always crits from the back just when i use find weakness which should be a gurantuued back hit it sometimes does not crit.