I had an armor stand in my world. It was covered in lether armor. I hadn't used my world in a while, and when I went back in, I found that the armor stand had leather armor... but it was sort of like iron armor... I tried breaking the armor stand and replacing it, then adding new armor, but it still displayed iron-like leather armor. I also tried moving the armor stand to a new location, but that didn't work either. In the inventory, the armor displayed normal leather armor. Maybe the new 1.12 version affected it? I had no active texture packs or behavior packs in the world.