Fences, iron bars, and glass panes often use an incorrect block state after conversion

The Bug

Converting from 1.11.2 to 21w43a some fences, iron bars, and glass panes became single.

Reproduce

• 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

World Download

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

Observed Result

The fences were and single poles

Expected Result

The fences would be connected