When a block or item is placed in the head slot that is not normally placeable in the head slot (such as with /hat from external plugins or cosmetics plugins/sidemods etc), the item on the head will not render in third person or in the inventory as it normally would when Pixelmon is not installed.
To reproduce easily/without plugins on both a vanilla client and one with Pixelmon installed:
Code: Select all/item replace entity <player> armor.head with minecraft:acacia_log
Without Pixelmon installed, the item will render properly on the head. With it installed, it will not be visible.
This also means pool floaties can no longer be "worn"- the summer vibes are DEAD