I guess this is a hard bug to fix, so they put on a warning instead

[Kozuki]

https://li.reddit.com/r/bladeandsoul/comments/86tns4/so_instead_of_fixing_the_true_heart_bug_its_now_a/

 

Wish they do the same to the description of Cat/Thrall Summoning skill: "Caution: Familiar can cause in-combat bug occasionally. Use SS and E or Escape to fix the bug"