The Bug:

Walls can occasionally turn invisible after upgrading old worlds.

Please note that this issue cannot be seen with fences, glass panes, or iron bars.

Steps to Reproduce:

• Launch an instance of 1.11.2.
• Build the setup as shown in the attachment below. setup.png
• Exit the world and upgrade it into the latest snapshot.
• Look at the walls previously were.
• Take note as to whether or not walls can occasionally turn invisible after upgrading old worlds.

Observed Behavior:

Walls can occasionally turn invisible after upgrading old worlds.

Expected Behavior:

Walls would not be able to occasionally turn invisible after upgrading old worlds.