Line in the middle of Stone Brick Stairs does not align when placed upside down.

Put the summary of the bug you're having here

What I expected to happen was...:
The line going through the center to be aligned with itself.

What actually happened was...:
The line is misaligned and it's cut halfway through.

Steps to Reproduce:
1. Place a stone bricks stair upside down.
2. Observe that the line is cut halfway through.
3. See image for clarity.