Issue: Pages not showing up in their proper categories (Sometimes)

There seems to be an intermittent bug where, after editing a page, the page will not appear in the expected categories. For example one of our users recently edited http://wiki.badgerandblade.com/USA_Virginia. After his edit the page text included [category]USA Shaving Supplies[/category], so it was expected to appear in Category:USA_Shaving_Supplies at http://wiki.badgerandblade.com/Categ...aving_Supplies. However it did not appear in that category.

This does not happen on every edit, but we do not know whether it has happened or not unless we double-check all the relevant category pages after editing a page.

The usual workaround is to edit and save the page, without making any changes. After that it usually appears on the correct category pages again.