When generating a superflat world with the preset 'The Void', the far southeastern block of the stone platform is missing. This appears to be the case no matter the seed.
To reproduce this issue, create a new superflat world with the preset 'The Void' and observe the issue.
The bug report that mine duplicates was posted later than mine, and it contains wrong information...
Edit: nevermind, I looked at the updated time instead of the created time.