World Doesn't Render, when i restart game doesnt save

Its pretty tricky to describe thats why i did a video shot. (https://youtu.be/nulqcCF53uw)

I am exploring away and when i head back the way i came some of the world doesnt load and there is like a big void.

i quit the game and it informs me that its being saved, but when i reload im in an old spot in the nether. lost all my inventory since that save.. so basically lost my progress within 10-30mins of game play.