I found that my soul cap will trigger at the start with the legendary ring and expire before and the damage doesn't feed into the ring it just explodes by itself.
I might have figured it out.
I engaged the 110 demon hunter at the Lorlathil flight point. Today I noticed some level 1 rabbits near the flight point. I must have killed the rabbits with the aoe from doa and said damage got added to the trinkets proc / stored damage.