by Séverin Terrier.
Hi Anna,
I'm not a specialist of recycle bin, nor backups ; sorry if i can't help much more.
Is your platform (where the problem occurs) well configured, with cron (and tasks) running regularly?
Perhaps you found a bug ; if it's the case, you'll definetly have to fill a tracker issue about that, with as much details as possible, and a link to/from this discussion.
Séverin