The faces of extra polygons added to a block model like Wooden Fences or Wooden Stairs do not use the designated texture. Instead they use a different texture with different texture coordinates and rotation. Changing the texture coordinates or rotation in the code wont change the outcome.

What I expected to happen was that the faces of the extra polygon(s) added would have the designated texture, right texture coordinates and right rotation.

What actually happened was that the faces of the extra polygon(s) happen to have a different texture from the one designated to it/them, together with a different rotation. The outcome could not be edited by changing the code.
(For example, I designated the oak wood plank texture to extra polygons on a oak_fence_n.json model file, the outcome is a nether brick texture.)
A screenshot has been attached.

Steps to Reproduce:
1. Use the Resource pack containing the oak_fence_n.json block moddel attached to this bug report.
2. Place a block next to a fence post.