The bug
After upgrading a world from 1.17.1 to 21w43a, some structures generate floating in air.
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Steps to reproduce
1. Create a world in 1.17.1 with the seed 1304268445 and render distance set to 12 OR download the attached 1.17.1 world
[media]2. Upgrade the world to 21w43a
3. Teleport to the following locations and observe floating structures
/execute in minecraft:overworld run tp @s 202.70 110.11 23.82 19.72 13.91
/execute in minecraft:overworld run tp @s 78.47 112.05 179.88 44.53 17.44
Notes
Note that this is likely related to world blending; there is terrain beneath the structures when recreating the world with the same seed in 21w43a.
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Related issues
Attachments
Comments


This is rare, and only happens on the border where old and new chunks are blended.

Rare? That's very subjective. Me and many people have very large worlds and see this often. I've seen this issue frequently in my tests.
Why is the resolution set to, "Won't fix"? You guys are probably super busy and have other things to prioritize. But you could at least keep the issue open and fix it in a later 1.18.X update.
Maybe I just don't understand how this works.