Redstone wire, powered rails, activator rails, detector rails and vines that are placed on top of a tile entity block (furnace, command block, dropper, etc.) in a structure file will break when that structure is loaded if the block that was below prior to the structure being loaded could not have supported them.
To reproduce:
Save a two-block structure: a dropper (or similar block) with redstone dust on top of it, then load that structure in empty air. The redstone will break and become an item.
Reload the structure in the same location, and the redstone will not break, because this time there was already a block positioned below it that could support it.
Try again with a regular block instead of a dropper and the structure will load normally in both cases.
I assume this happens because tile entity blocks are handled differently than regular blocks when loading a structure, but I have no idea why this happens with redstone wire and special rails but not regular rails or other blocks that require support like carpets, torches, or repeaters.
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As stated above, this appears to be a duplicate of MC-104231
Don't see how this has anything to do with that issue? MC-104231...
only affects rails, not redstone wires
affects regular rails, which this does not
doesn't require the block beneath the rail to be a tile entity
results in the block being improperly rotated, not broken entirely
This might be a different bug entirely, but something similar happens with carpets, just much less consistently. Can't be reproduced with just one carpet on a dispenser, but happens with a 3x3 of carpets on dispensers. A couple carpets usually remain unbroken, and which ones stay don't seem to be random, but I can't tell what's causing them to break the way they do.
[media]These are all the same structure loaded in at different locations, see how different carpets stayed sometimes. No idea what causes this. Other than the carpets sometimes staying, they completely match the behavior of this bug.
Also can confirm for 21w16a
can also confirm this is still an issue in 1.18.2
specifically for me it was unpowered repeaters on top of barrels and command blocks
Resolving as a duplicate of MC-188789 since this is the same issue.
Relates to MC-129206