Stance bug is known for months. Ofc it's not getting fixed because BHS can't be bothered and GF don't care.
As for the Backstab change - it's for all classes with that skill. Now you know how using Cable Step (the hook skill) with reaper feels like if your ping isn't great.
It's been a few months since mystic's Boomerang Pulse got bugged (can't be used when aiming down, so it's useless if you're above your target's level and want to heal/damage them) and GF have done nothing about it because they can't fix it on their own, so they don't care.
Vow of Rebirth - bugged for years (can be dispelled with Plague and Regression) - GF don't give a shit.
Motes going on cd if you dare to move while casting them - not fixed.
Valkyrie stunning knocked down targets - not fixed.
Valkyrie hitting through walls (i.e. without a line of sight) - not fixed.
Reaper's Retribution not working for attacks other classes can avoid with similar skills (for example the wave attack in RK HM at last boss or the rings in LK HM at last boss) - not fixed.
Not to mention the dropout-upon-logging-in bug.
Giving these examples just so you know what to expect - no action from GF. So either write on the Korean forums, or learn to live with these bugs. 



