I have a human-only PB and I had the power slotted into my AOE blast power but it never seemed to proc. I also never saw it proc on any other power.
I found a post from a while back (do a search for Essence Transfer in this forum) where someone suggested the proc was broken and either not actually global or didn't work in AOE powers.
So I moved the set from my AOE blast to a single target blast and it's working way more now. I did a test and it seemed like it was proccing from my T1 power as well. So I think moving it out of orbiting death and to a single-target power might work better.