When using commands to give myself a diamond sword with the "Unbreakable" NBT data tag, the diamond sword icon was gone, replaced with a missing block model. Some experimentation revealed that any item with a durability that is given the"Unbreakable" tag has its icon or model replaced by a missing block model, from armor to tools to weapons. Writable books with the "Unbreakable" tag also had this issue. There are two exceptions that I found: the Bow, which instead shows the icon for a bow in the process of being drawn, and the Fishing Rod, which instead shows the icon for the fishing rod when it has been cast.

What I expected to happen was...:
The items with the "Unbreakable" NBT tag should have been no different in appearance to the normal items.

What actually happened was...:
The icons for items with the "Unbreakable" NBT tag were replaced by missing block models, with the exception of the Bow, which instead showed the icon for a bow in the process of being drawn, and the Fishing Rod, which instead showed the icon for the fishing rod when it has been cast

Steps to Reproduce:
1. Type the following into a command block in creative mode: /give @p diamond_sword 1 1

2. Trigger the command block with redstone.