Originally posted by Estyn:

I've had this happen before on both stone and wood structures. There seems to be no discernable reason for the single piece to collapse... fully supported, proper alignment/snapping, etc. Go away for a fairly lengthy period, come back, that lone piece will be broken again, even though everything else is fine.

Perhaps there is some internal non-visible issue like an old landscape artifact, invisible rock, etc or something that's interfering. I've never been able to solve it.

Yeah I suspect the same, or some internal data structure gets into an inconsistent state. I replaced the single 4x2 with four 2x1s, and it hasn't happened again since. If it does I'll mention it here.

I've had this happen before on both stone and wood structures. There seems to be no discernable reason for the single piece to collapse... fully supported, proper alignment/snapping, etc. Go away for a fairly lengthy period, come back, that lone piece will be broken again, even though everything else is fine.

Perhaps there is some internal non-visible issue like an old landscape artifact, invisible rock, etc or something that's interfering. I've never been able to solve it.

So this has happened two or three more times to the same block. It's the only block that this has happened to. On the last occurrence it actually dropped the 6 stone. None of the other occasions resulted in any stone being dropped. The block that is disappearing/destructing is in green stability, The blocks on either side are green, and the row of blocks it is sitting on are in direct terrain contact and are blue. I'm going to try replacing the single 4x2 with a couple of smaller blocks and see what results.

it's the Enderman it's his hobby!

Is it possible that a block just on the edge of stability loaded in before its supporting neighbours?

Thanks, I'll check that block's stability. It's only one row up from terrain so it should be solid. Also when blocks are destroyed by instability isn't the stone always dropped? I didn't see any dropped stone.

it's the Enderman it's his hobby!

happened to a base i made once. i finished my base (more like a house), and next time i went to visit it, a few months later, the base was unfinished, roof not done, only one room was finished, and all my carts with resources were there, almost like it just stopped saving at some point and reverted back to a prior time while i was constructing it. i never finished it after that.

this has happened to me twice. Both times, it turned out that the offending block was, somehow, unstable (red) and was destroying itself after a fairly long delay. Something in the computations determined that one was bad (I had like 5 more blocks high on everything around them, in both cases). Try embedding a larger block into its neighbors to improve support when you fix it. That has worked for me on these. It seems like a rare bug, possibly some sort of floating point roundoff or similar numerical issue that caused an incorrect stability calculation.

Happened to me as well. It happened to pieces that were in yellow to orange stability, which is annoying because they should only collapse when in the red. I braced up my building with wood iron poles and it fixed the problem.