When right clicking (interacting), the following code is only called if the player is OP:

@EventHandler
public void onInteract(PlayerInteractEvent event) {
   try {
      System.out.println((new Random()).nextInt());
   } catch (Exception ex) {
      ex.printStackTrace();
   }
}

I have tested with only PlugMan and this code running, and the same issue occurs. What I did notice was when I had PermissionsEx installed, this was broken, but when I unloaded PermissionsEx via PlugMan, it fixed, but then when I stopped the server, disabled PermissionsEx, and started the server, it broke again.

PlayerInteractEvent is a vital event for the majority of plugins and thus I have put this as a major bug.