I hadn't realised that I had the latest snapshot enabled but it appears that I have no upgraded my world to latest snapshot which appears to have a number of bugs..

This bug is easy to find. Have an existing world with a furnace (can be either fuel or not fuel enabled). When you load into the world using the latest snapshot, all the furnaces appear to be empty of fuel (e.g. coal). Add coal and the game crashes - see attached crash log.