I have encountered a strange and unexpected problem. In the Posts >> Categories screen, the Categories list has gone missing, including the "Uncategorized" category. The individual posts under the categories are intact, although in the "Categories" tab in the Edit-Posts screen, I get to see the top-level category names (and not the sub-categories). Clicking on the correct top-level category does not have any impact. The tags list for the individual posts shows tags that belong to some other post.
I have also installed the Page-Category plugin (Misiek). The page categories are intact in the Pages >> Categories screen. Also, in the EDIT of the individual Pages, the Page Attributes and the Categories are set correctly. However, in the frontend, the corresponding widget for Page Categories shows no listing of the category at all.
I transferred the database and the WP environment to localhost, and amended the appropriate files (wp-config.php, wp_options, wp_posts) and set up the site in localhost. Here, not only are the post-categories showing up correctly, but also the tags are correctly linked to the individual posts. The page-category list also shows correctly in the widget in the frontend. The site on localhost is absolutely without any problem.
In phpMyAdmin, wp_mpc_categories and wp_mpc_pages_categories tables are intact. (That is why the localhost site is working perfectly!) This is so for both the localhost database as well as the live site database - they are mirror images of each other.
What could have gone wrong? This looks like some sort of wrong indexing to me. Wrong indexing which did not get carry-forwarded to the localhost environment. Any guidance from WP gurus and experts is most appreciated.
I have the following plug-ins installed:
1. Akismet 2.4.0,
2. Fast Secure Contact Form 126.96.36.199,
3. Misiek Page Category 2.2,
4. WordPress Database Backup 2.2.3 and
5. Wp-Members 2.3.2.
Of these, the only plugin that I remember upgrading most recently is Akismet.
Thanks in advance.