On the chest island here you need to hit 4 pillars with a hammer, after completing the puzzle natural resources can spawn on the sunken pillars making it so you can't hit them without trying to hit it while the cursor is going between 2 tiles, which is pretty hard to do. Also when trying to place bridges quickly a similar thing can happen and the sprite for the bridge isn't aligned with the hotbox, but the sprite blocks you from placing a bridge on whatever tile it ends up on