products not appearing in their category?

Hi everyone.

I usually create a category, for example in my keyrings section of my shop, I would create movie keyrings, video game key rings, comic book keyrings etc..
Never had any problem. However, one I just added / created is not working properly. The item I added to it and created it for is not appearing there, although the category itself is showing up, but nothing is there.
Has anyone had this happen before? or know the fix? or is it usually just slow to update?

Thanks in advance