WowAce

Pretty simple really. Instead of being counted as healing, all absorbs from the Brewmaster Talent "Guard" is being counted as Overhealing.

As it's impossible to overheal with the talent (It causes you to absorb the damage you would stagger instead, so it's not even a true absorb, so it can't even overlap other absorbs), this is clearly a bug. I tested this many times with the training dummy in Boralus and in dungeons.

No matter what, I would absorb the damage with Guard, but it'd always show up as Overhealing and not Healing.