Lady Vashj Bug

So I tried collecting the Corruptor Raiment and I can't get the full set. I need to kill Lady Vashj in Serpentshrine cavern in order for her to drop a specific item. When I enter the second phase of the Lady Vashj boss fight, the lantern things that I'm supposed to destroy with tainted cores simply don't appear. My only assumption is that, in order for it to work properly, is to kill all the bosses, but I can't kill The Lurker Below, I can't fish him out because fishing is an action that "is not available in the area". I don't want the alternative hood that I can buy Area 52 because I already have the full set (except of the belt because The Lurker Below drops it, but I found another one that shares the same model). Has this happened to other people or is it just me? Is this a bug that came with new update? My friend told me that he killed Lady Vashj long ago and that it worked properly for him. Can anyone help me with this?

you can burst lady vash if u get a group therefore preventing it from entering stage 2
it is possible to fish the lurker but over many attempts as sometimes u will be able to fish in that area