For example, go mine some gold.
Try and make a gold sword after you smelt it, and it works.
Type /stack, and you can no longer create gold sword until you make new sticks that have not been /stack'd.
You can still make leggings, and stuff though (Maybe a problem with the sticks?)

I can no longer use any of my 8 diamond that were in my inventory when it was /stack'd, no leggings, no sword, shovel, etc.

This belongs on...
https://github.com/sk89q/worldguard/issues

Whoooops.