[1.12.2] Issue with custom armour models.

So I recently started working on a custom armour model for my mod. But I came across an issue with the rendering of some armour pieces. The helmet and chestplate work just fine, but when I equip the leggings, it shows the model for the leggings, the chestplate and the boots, even when the chestplate and boots are not equipped. Similarly, when I equip the boots, it will also show the model for the leggings (again, even when the leggings are not equipped). The final issue is that when either the leggings or boots are equipped, the legs no longer move independently from each other. It's a weird thing to see and is hard to explain but there is an image attached to this post that shows you what I mean.

Here's all the relevant classes from my mod:

ItemInit: https://pastebin.com/zNjbEYiW

Armour: https://pastebin.com/L4cfFJaA

Model: https://pastebin.com/W28eHEEt

Other than that, everything appears to be working fine.

Any insight as to what's gone wrong here would be much appreciated.