The bug

The game's rendering engine doesn't behave correctly in F5 mode when the player crosses chunk borders.

How to reproduce

1. Make a wall at a chunk border, direction (XYZ) doesn't matter
2. Dig 2 blocks into the wall so that the player can fit in
3. Stand in the hole, face the other chunk and make sure that there's a block above, below and next to the player on both sides
4. Press F5 twice to open the front-view and move out of the hole, blocks which weren't rendered while standing in the hole are now being rendered