If you leave minecraft with a item for example a moss block. When you rejoin it will be a moss carpet. This happens with the stated blocks below

Wool. Turns to carpet

Moss. Turns to carpet.

Wood. Turns to slabs.

Cooked beef and chicken. Turns to raw beef and raw chicken.

Pressure plates (gold and iron)  turns to gold and iron nuggets.

Chests. Will be ok but all food and ores will dissapear.

Steps to reproduce:

1. Hold the items shown above
2. Leave the game 
3. Rejoin the game 

Observed results:items will be changed or missing

Expected results:

Items will be the same and not missing