I was exploring the new nether biomes, when I noticed that the ghasts were partially invisible, and the non-invisible part was made up of the iron armor texture. I was using a Vanilla Tweaks texture pack, I reloaded the pack, and it seemed fixed. I then noticed that my Iron Armor had the texture of some of the ghast parts. I managed to get a screen shot of the ghast armor, but not the ghast with the iron armor texture. I tried it both with and with out other resource packs, and it seemed to affect every one.