[Archer] Find Weakness bugged?

Is the find weakness skill on archers bugged? It is nearly impossible to not crit on thunderbolt on a backstrike with my current crit factor but i noticed that sometimes when i make use of find weakness it does not crit, is that bugged or is the game just so poorly optimized that server cant keep up with the bosses movement so if u use find weakness sometimes the game does not know its a backstrike?

Quote from Astarte

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.

Quote from hamamah

rngesus said no so it didn't crit

i don't see any bugs with it even with +260 crit rate thunderbolt can be white damage

Ya i figured was just irritated coz i did not use it for a while and always crit.

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