When I installed WP No Category Base on our site everything seemed to work fine.
Then I realised that the category pages, i.e: domain.tld/category1/ domain.tld/category2/ each displayed *all* posts, even if most post were belonging to other categories.
I un-installed the plugin, but the behaviour stuck to the site.
I even tried to empty the proper sql rewrite table, and have wordpress rebuilt it, via the permalink page, to no avail (wordpress rebuilt it almsot exactly the same). I then tried using a fresh .htaccess file (like the one in place before), with no success.
I did try the newest version of the plugin on an empty site, and I could not reproduce the behaviour. It seem it depended on a previous version, but now our site is stuck with unusable category pages.
What can I do to reset the rewrite rules responsible for that?