I think I found a bug where Scent of Blood is not being consumed when you Death strike in unholy presence NO scent of blood charges were being consumed at all.
Heres the video youtube(dot)com/watch?v=NeSzXt8sCcY
Heres my armory link battle(dot)net/wow/en/character/stormrage/Scharlotte/simple
Some more info is that it was consuming the charges when I swapped back to blood presence.
I was basically running around tanaan spamming death strike.