Same here, one exalted and two grand sacrifices gave me zero hearts... but I'm pretty much used in getting nothing from "special" events. Luckily, I was pushing for a vortex fill, buying some more souls and, after that, I got five hearts plus 25 G/A souls. After more sacrifices, including those hearts, I ended up getting a Lgendary and some sentinel plus rare souls. Which gave me - again - nothing new. Dupe power!
The only gain are some skill shards, not sure how many, but at least 10. Which is good.