When the player's inventory is open, the currently held/equipped item from the player's hotbar does not show in the player's hands. The player has their arm(s) tilted as if they are holding something, although the item itself does not show. This happens both in the survival inventory and creative inventory with the Survival Tab selected.

This does not apply outside of the inventory menus, as when you change perspectives, the items in players' hands are visible.

Blocks are shown correctly. Only 2D items do not render on the inventory player model.

Extra info that might help: MOST blocks are shown correctly, I tested with some transparent blocks like lime stained glass and it wasn't showing in the inventory menu. Also, this only applies with the new "Fabulous!" graphics setting.