u/Electronic-Bread-147

So I just built this creaking farm and none will spawn!! I have the creaking hearts on the backside of that pale oak log wall (shown in 2nd pic). I have no idea what’s wrong. The hearts are most definitely in range of the spawn area (the hoppers). And as far as I know they can spawn on hoppers. There is nowhere else available in range for them to spawn. I waited all night and none of my 4 hearts spawned one. I’m so confused!! I’m on survival, normal difficulty, on a Java realm. Please help!!