The bug

The /fill command fails to replace blocks with air when large amounts of blocks are removed from underneath redstone components. When the command is run a red message appears in the chat saying something along the lines of "an unexpected error occurred". Often (though not always) all of the blocks are removed, however much of the redstone is left floating in the air. Screenshots of the issue and the setup I used for testing are attached.

After a bit of messing around, it seems like 858 is the maximum number of blocks I am able to remove without this occurring. As soon as I create a platform of 859 blocks or larger, this error occurs consistently.

It only seems to happen with redstone components. I tried it with redstone dust and repeaters and the bug occurred, however when I used normal torches I was able to clear a 30x30x30 block without any problems.

How to reproduce

1. Create a stone platform at least 859 blocks large (30x30 works)
2. Place redstone dust on every block of the platform
3. Use /fill to remove the stone