Custom Zombie Villager Model Showing Through Armor

I've created a custom zombie villager model. It has the exact same outer body size as the standard zombie villager, and its expand is set to less than the standard zombie villager. Yet for some reason the chest armor model looks fine on the zombie villager model, but the outer body layer peeks through the front and back on the custom model.
Using block bench.
For reference the armor model is 4 deep with an expand of 1.01
Vanilla zombie villager outer body is 6 deep with an expand of .5
My zombie villager outer body is 6 deep with an expand of .3
Both the standard and mine SHOULD peek through front and back. Only mine does, despite having a lower value for expand.