Missing/Not Loaded Blocks

What I expected to happen was...:
Some New Things Added To The New Snapshot Update To Try Out & Play.

What actually happened was...:
Most Of The Blocks Didn't Load & When I Tried To Go Back To A Previous Version, I Still Had The Same Problem. The Only Way I Could Get All The Blocks To Load Was Going Back To Snapshot 14w26b, but even then I still had some issues. Like some of the signs were missing text, also the pistons weren't retracting when there was no light to activate the daylight sensor. Also, ever since the 1.7 Update there was an area in a square shape where blocks were missing & couldn't add blocks. I could see all the way to the bottom of the world, when i enter this space. It acts like I've exited the game map.

Steps to Reproduce:
1. Startup Minecraft
2. Select Single player
3. Select World aka Erikmons World