I've noticed that chunk frustum culling sometimes works incorrectly and removes chunks that must be visible.

How to reproduce:

Create a superflat world (with cheats enabled).
Set your FoV to "Quake Pro".
("Normal" or a bit lower ones also work, but the bug is less apparent on them.)
/tp @p 0.05 4 1 -50 0
(You don't have to be that close to the chunk border, but this way it's easier to see the bug.)
/fill 0 4 0 15 6 0 stone
/fill 15 4 0 15 6 15 stone
/fill 0 4 15 15 6 15 stone
/fill 0 6 0 15 6 15 stone
Now you can see that the entire half of the visible world (located on the other side of the chunk border you're standing next to) is not rendered.

Exact conditions:
1. There must be no path from your location to any border of the current chunk except a single side border.
Above mentioned path has to be obstructed by opaque blocks, transparent ones (like glass) don't work.
2. The only unobstructed chunk border have to be behind your back.
The precise condition is that the angle between your line of sight and the normal to the chunk border has to be less than 45 degrees.