I am leveling a Barbarian right now and I cannot get this aspect anywhere. It does not show up in my codex, I completed the respective dungeon twice, and I can’t find it in the occultist.
The name of Aspect of Unrelenting Fury was changed to Aspect of Voracious Rage.
Side note: The aspect can be used on all classes now, but Barb’s usage is bugged as it still refunds Fury on Boss hits.