Diamond chest plate disappears

Put the summary of the bug you're having here

What I expected to happen was: I tried to grab my diamond chest plate off of the armor stand

What actually happened was...:
There was a lag. After the lag suddenly "caught up", I had broken the armor stand and all of the diamond armor that was on the stand was in my inventory, except for the chest plate which disappeared.

Steps to Reproduce:
1. Approach armor stand with full diamond armor on it
2. make sure you're in multiplayer and that there's a lag
3. try to grab the diamond chest plate