Category & Tag Archives not displaying

Something weird has happened to 3 blogs of mine hosted on the same server, but running on different domains and different SQL databases. One is still at 2.9.1 (oops), the other two were at 2.9.2, I upgraded one of them to 3.0.1 but that hasn’t helped.

The problem – click on a category archive and no results are displayed. Obviously, when one is running magazine and portfolio sites this totally screws up the display of entries.

There is also a fluctuating problem whereby sometimes the tag archives will display results and sometimes not. Also, in admin on Edit Posts the posts are all now displayed as Uncategorized and no tags, but when I look at Edit Tags or at Categories then they are all listed there and displaying their attached posts count.

The archives-listing page still lists all the categories, but when they are clicked on then no results are found (displayed) for that category.

However, the monthly archives still return and display results/entries. Search results still work fine.

I’m totally flummoxed by this. I need to have an idea what could possibly be causing it so that I can communicate with my reseller host about what’s going wrong.