This bug causes some trees of the world to be generated only on the X or Z coordinate of the tree trunk. I have played around with the new parameters like biome size and ore generation etc... which may cause the bug. I have seen it most often on single trees in the plains biome but also on hilly forest.

What I expected to happen was...:
Trees would be generated completely, 3D

What actually happened was...:
Trees are only generated on either one X-Axis value or on only one Z-Axis. It is only the X/Z value of the trunk, which makes it look 2D.

Steps to Reproduce:
1. Change the world settings to non-default, fore more of this trees.
2. Let the world generate move around and look for this trees, most frequently on areas with very rare trees (plains, etc)