I don’t exactly know how this happened but I feel like I’ve ran into this same scenario before. I am not completely sure how to reproduce this problem either. Maybe it’s forbearance?
Basically Soulstone is simply not working in this scenario. I have proof in this video that I have 3 minutes left on the buff, I even call it out before I die and it doesn’t do anything at all. This is clearly a very obvious bug.
