The bug: You can hover your mouse over the bottom of the pillars and they will highlight through the ground. My assumption is that you should only be able to highlight them and click them when aiming at the top of the pillar that sticks out above the surface.

How to reproduce:
1. Go to Fiery Forge
2. Find one of the pillars (the ones in the boss room especially) and hover your mouse at the base of the pillar below the surface.