If you open a chest and place a block on it at the same time you can open the chest and sometime the block will disappear.

Put the summary of the bug you're having here

*What I expected to happen was nothing i was just messing around with the hay bales

What actually happened was...:
When I place a hay bale on a chest i did it in such a way that it allowed me to open the chest with it on top but the hay bale disappeared.

Steps to Reproduce:
1. Try to place a hay bale on a chest but at the sametime try to open the chest
2. Repeated until the hay bale disappears (it may take a while I've only recreate it one other time