Short Version:
Can not place PStones inside global WorldGuard region.

Details:
I have a world set up as a "Hub Town", so the entire global region set up in WorldGuard does not allow building (much like vanilla server spawns). Priority is 0.

Within this global region, I have several plots set up for players to build in, which they can no problem. Priority is 100.
The only blocks they can not use are the protection stones.
In the main town (streets, etc), placing a stone gives the standard "You do not have permission here" message.
In the plots, it says something along the lines of not being able to because it overlaps a worldguard region that the player is not allowed to be in.

Again, this only conflicts with global. In another vanilla world, players can use PStones with no problems and are denied building in worldguard cube regions with "Build:Disabled" flagged. (Towns, waypoints, etc)

I tried:
To add it to the bypass sets: Could place block but no field was created
To add the bypass permission: Could place blocks and field, but could create them everywhere (Even other people's fields)
Deleting the global region- worked, but my hub-world was exposed to grief.