What you were expecting to happen, and what actually happened:
I was expecting to get an improved drop from my epic vault key, but it gave one single copy of Heart of Rage (which is the exact same drop one can get from Cedric using a regular vault key)
How often does this happen? When did it begin happening?
As far as I can tell, it should happen every time King Cedric drops a Heart of Rage
Steps to make it happen again
Find a (very rare) epic vault key, get the (very rare) Heart of Rage drop and get disappointed
That’s what the patch notes claimed, but others have posted screenshots with 2x major orbs, 3x minor orbs and 4x troops from an epic vault battle… Only heart of rage seems to not be dropped in multiples, it might be intentional but I still think it’s underwhelming
Edit: found a screenshot to prove this point, a 4xCedric drop from an EVK