https://www.youtube.com/watch?v=Pgwu10S6heY
video
This happens when you push two slabs against the world border and then push them with a piston there is no hitbox whatsoever and you can place blocks, however you can still collide with them.
Happens in 1.21.11 and 26.1 Snapshot 10
Environment
Should occur on all pc specifications if i am correct, as it is in the game version
Linked issues
Comments 2
Thank you for your report!
We're tracking this issue in MC-82010, so this ticket is being resolved and linked as a duplicate.
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Duplicate of MC-82010