When i jumped on the cobble wall i noticed that you are hovering when you are in F5 mode.
Easy to reproduce, hopefully easy to fix.
Environment
Os: Windows 7 Pro x64, Java 7 64-bit,
MC-2515
Hovering over cobblestone walls
Resolved
Duplicate
0
It's a side-effect of them being 1.5 blocks high. So working as intended.