The off-hand hotbar slot is missing

The additional hot bar slot that would show at the bottom of your screen when you're holding an item in your left hand is missing. I'm currently holding a map in my left hand for this slot, but I don't see the additional item slot near the hot bar.

Steps to Reproduce

• Create a map.
• Place it in the off hand slot.
• Notice that the off hand slot never appears near the hot bar.