PlotSquared Walls Not Generating Properly

Hi,
I have a problem with PlotSquared, specifically on my Creative server. I generate my world with these settings:

Code (Text):

  plot:
      height: 64
      size: 96
      filling:
      - '3:0'
      floor:
      - '2:0'
      bedrock: true
      biome: FOREST
      create_signs: true
      auto_merge: false
    wall:
      block: '44:6'
      block_claimed: '44:6'
      filling: '2:0'
      height: 64
    road:
      width: 7
      height: 64
      block: '155:0'
    event:
      spawn:
        breeding: false
        egg: false
        custom: true
    economy:
      use: false
      prices:
        claim: 100
        sell: 100
        merge: 100
 

But when I go to the world, the walls of the plot do not generate properly. They generate with the default stone slab with a few random nether slabs (what I actually want as the walls) scattered around.
Here's a screenshot of what it is: http://imgur.com/TXp0sk5
Here's a screenshot of what it should look like (
minus the roads): http://imgur.com/Pgpeodu
Here's a list of my plugins:

The world generates fine on every other server I've tried except for this one. It must be a plugin, but what plugin could possibly be causing the plot walls to not generate properly? I've tried restarting, checking the console, and re-installing PlotSquared. It always fails to properly generate.

Thanks for your help!

EDIT: Not running latest version of Spigot. Updating fixed the problem. Stupid mistake, sorry :/

 

Actually, I noticed that the other servers I tried it on were 1.8.8 and the server that wasn't working was just Spigot 1.8. After updating the one that wasn't working to 1.8.8, the walls started generating properly. The devs of PlotSquared said it was tested with 1.7. 1.8, and 1.9, so I guess it's just a bug on their 1.8 version and worth reporting.