I noticed this bug yesterday, wherein it says that someone posted in that thread recently, but when I check the thread, the post isn't there. I have tried refreshing a lot but, it doesn't work. Help?

Going on the assumption that it's not a forum bug:

Check to make sure your browser isn't forcing a cached version of a certain page, I know this sometimes happens when your browser detects a poor connection. You can completely force refresh a page by using ctrl + F5.

Another possibility could be that a certain person posted and then removed the post thereafter.

Try running the same checks on different browsers, also I think if you would like a proper response perhaps screenshots and links would be needed.

If however, it is as you say - a bug, then you'd most definitely need the above information available for moderators to pass on.

Thank CoKe, I will try the tips and if it still doesn't work, I will take pics.