[Gameplay Bug] Rek'Sai's Passive Issue

Playing a game of ARAM recently, I noticed that although the health packs do refill a bit of Fury, it doesn't count towards the healing from Fury of the Xer'Sai if she's already burrowed and out of Fury. I'm yet to test this bug extensively, and I admit it's far from gamebreaking, but it was rather confusing that being burrowed with Fury wasn't healing me at all.