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
Environment
Microsoft Windows [Version 10.0.15063]
Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz, 3.40 GHz
64-bit operating system, x64-based processor; 8.00 GB RAM
NVIDIA GeForce GT 630; GeForce Game Ready Driver Version 385.28
Java 1.8.0_144-b01 (64-bit)
Dupe of MC-63070