Converting from 1.11.2 to 21w43a some fences, iron bars, and glass panes became single.
- Create a world in 1.11.2 with the seed: 351686644826372386
- Fly towards 515 ~ 705 (You should see a village in the distance)
- Leave and enter the world in 21w43a
- Fly towards the village
download the world here and go to there coordinates: /execute in minecraft:overworld run tp @s 631.19 64.38 593.94 -122.70 39.75 to see the issue
The fences were and single poles
The fences would be connected