I am on v1.2.7
Playing on realms, the game keeps locking up when walking around, seems to do it in the same spots. The chunks should be loaded based on view distance.

Using the table above as an example, if I am walking in a straight line from block A, heading to Block 1, whenever I reach block P the game locks up and stops responding. I can't use key strokes (for example CTRL-ALT-Delete) to get to the task manager to kill the game (CTRL-F4) to kill the game, or (ALT-Tab) to switch out to another program. The only way to recover (and I have waited up to 15 minutes) is to hard power off the computer, and restart it. When I log back into the realm, my character will be sitting at block L or M, instead of P where the game locked up. After logging back in, I can then walk to block 1 - 6 and walk around normally, I can then walk back to blocks A-L without issue, but if I immediately turn around, and try to walk back to block 1, when I hit block P, the game stops responding and locks up again. It only seems to happen going outward from the center of my base. This happens in multiple places. Started with this last update to the game.

I can reproduce this on 3 different laptops.
Another bug is that my base is built into a mountain, I can log out in the middle of my base, lets say at 160,64,16 and then log back in, I will be logged back into the world at the top of the mountain 160, 120, 16.