Hi,
If you move a post and leave a redirection link - it vanishes.
I made one earlier here, and selected one day, but made no comment.
It has now gone.
On my forum they are vanishing almost immediately.
I have tried both 1 & 2 days on my forum (and 1 day here) - with and without comments - all just vanish.
This is 7.1b5 on both sites.