Slime Against Humanity didn't get a boost from my graveyard

Edgar

This card says it makes 4 Ooze tokens, then they get +X/+X equal to the number Oozes plus the amount of Humans in graveyards.

I had 4 Humans in my Graveyard, but the Ooze only got +4/+4, which it gets when I have none in my graveyard (expecting +8/+8, or +5/+5). Playing another game against AI, and getting a Magering Bully (Human Warrior 4/4) in their graveyard, SAH still only gets +4/+4.