I put Diamond Horse Armor onto a Horse

What I expected to happen was...:
I expected to have a armored horse to ride around on

What actually happened was...:
The horse became invisible and only becomes visible when I take the armor off, when I killed it by dropping it with a lead, my screen turned red

Steps to Reproduce:

Step One: Put Diamond Horse Armor on Horse

Step Two: Pick invisible horse on lead

Step Three: Kill it by slamming it into the ground

Step Four: Results