Glitches and Crashes

The glitches occur when you minimize the game. Once reopened, your avatar is missing. There are some items missing as well such as beds and chests and when pistons are in use, part of it goes missing. Also, when you invite a friend to your world, you either appear invisible to them or they are invisible to you. Also, a black glitchy blob appears on your screen when you move to a certain angle. As for the crashing, when you try to join a friend's world or server, it immediately crashes the game. Also, you can't seem to see your friend online or join their world.