After having loaded into my world, I realized that my armor stands had nothing on them besides a weapon. I left triggered (LT or Right Mouse Clicked) the stands and got my armor pieces back. I tried to place them, but they turned invisible. Even if I destroy the stands and put them back down, the armor is still invisible when placed on the armor stands.

This problem occurred for me after the 1.12.1 bug fix update for Bedrock Edition on September 3rd.