Iron bars render incorrectly when looking at them from the East.

Iron bars should have rendered the normal bar pattern

Iron bars on one end rendered only the border bars.

How to make this happen:

1. Place iron bars going east to west.
2. Look at the leftmost bars from the east.
3. Some bars are gone.

NOTE: Works with any height of a wall, I think. I tested it with a 2 bar high wall too.