Cannot block with sword when facing a fence post

When trying to hide behind (facing towards) a fence and blocking with a sword, the expected blocking action/animation does not happen. Instead, the "activation" animation (i.e. what happens if you're holding a sword and right-clicking on a button, fence gate, etc) occurs. I'm not sure if this is purely visual and I'm actually blocking, or not.

What I expected to happen was...:
When I'm holding a sword, I can block by right-clicking even if I happen to be facing a fence, since it's not interactive.

What actually happened was...:
The button/lever/fence gate activation animation is shown and the sword doesn't block.