Hello,

There is a bug when you have a Elevator and do the command to increase the height. That foundation does not take any damage and can not be destroyed.

Update: 

With this plugin loaded, when you put just 1 elevator on a foundation without running the command. You still can not destroy the foundation.

There is no such restriction in this plugin, you can still destroy foundations with it loaded so you must have something else on your server that is preventing damage