It seems that the footer issue is updated when someone just logs in and out.
Bug still there
There is no any bug here. The footer information is cached for better performance and it's being updated not in real time.
The statistic cache is collected differently. Also this could be database issue. I don't see such problem here at wpForo.com.
Very unlikely to be a database issue. It only happens if the post in a private forum.
Do you have content in a non public/private forum here?
To be clear this bug is not critical for me at all. I would be happy if the "latest post" did not appear in the footer at all. In fact I will probably remove it with CSS anyway.
Just tested it on a dummy board, posted in a private forum; "latest post" in the footer is blank - does not show anything.
Deleted that post then the latest post from a non private forum shows up in the footer.
Looks more like the filtering logic is broken, not a database issue.