While wearing Elf Bane on PTS, if you cast burning embers and wait for it to expire, you will not get the heal but will get it if you recast the skill early.
Found that out while hitting the dummy and using Spell Symmetry.
I'll check when I get home in about 20-30 min. There's a hidden buff that lasts like 1 sec longer than burning embers that is the counter effect for the heal I believe. I suspect the duration isn't increasing properly.
EDIT: Yeah, exactly what I thought. The hidden internal (de)buff on targets with Burning Embers up isn't long enough to cover the new Elf Bane duration. It's set at 16 sec which covered the old elf bane duration bonus. I submitted a bug report in game so hopefully that gets through in time to be fixed for Harrowstorm on live. Pretty major losing that much potential healing if you're waiting until last second to get a big heal.
Also just to clarify, while wearing Elf Bane, as long as you refresh burning embers OR it ends within the first 16 seconds of the dot duration, it will heal you, but in that last 3 sec window it won't heal at all since the internal (de)buff fades.