The corridors/open spaces in some (primarily older) structures don't generate filled with air blocks but seemingly no blocks at all (i.e. a vacuum).
Steps to Reproduce using the Mineshaft as an example
1. Find & enter the Structure
/locate structure minecraft:mineshaft
2. Check the supposed Air blocks in a Mineshaft corridor
# Using '/execute'
/execute if block ~ ~ ~ air
# Using '/fill'
/fill ~ ~ ~ ~ ~ ~ glass replace air
3. Receive an Error Message because no Air blocks were found
# Result of '/execute'
Test failed
# Result of '/fill'
No block were filled
4. Optional: Place any block at the target coordinates by hand, remove it & execute the command(s) from step 2 again to receive the expected result of Air blocks being detected
# Result of '/execute' after Block Update
Test passed
# Result of '/fill' after Block Update
Successfully filled 1 block(s)
See the attached videos for a demonstration.
Based on what I've tested, the game's oldest structures which haven't been (majorly) updated since seem to be affected. The bug has probably always been in the game, but I couldn't find an open bug report discussing it.
Affected Structures | Unaffected Structures |
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Thank you for your report!
We're tracking this issue as MC-125135, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as Won't Fix, which means this is considered a bug but won't be fixed. The description of that ticket or the comments might explain the rationale. Please do not leave a comment on the linked ticket.
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Not a bug. They use cave_air, not air. See also MC-125135.