Walls not connected to some blocks in ancient cities.

When the wall around the "portal" is generated in ancient cities, the walls do not connect to the blocks generated in the structures around the wall.

Steps to reproduce the issue:

1. Go to seed 0 (Example).

2. Go to coordinates -19038 -46 2687.

3. Look at the wall, and notice that the walls do not connect to the blocks around them.

Expected result:

Wall blocks connect to all blocks.

Actual result:

The wall blocks do not connect to the blocks of structures other than the wall surrounding the "portal".