Taxonomy Permalink not activating

Hi

For my posts, I have set up a category with the name “News”, with a slug of “news”. It has an id of 22. Under this I have a second category, called “Success” with the slug “success”. It has an id of 33.

My permalink structure is this: /%year%/%monthnum%/%category%/%postname%/

I’m using a drop down list to allow users to select the category they want to see. Basically, I submit the form to the frontpage of the site with a query string appended of cat=<id>.

For the success, child category, this ends up being 301 redirected to the pretty URL of “/news/success/”. This is good, and is what I want.

However, the “show all” option, cat=22 should be 301 redirected to “/news/”. But is not. However, both urls, /?cat=22 and /news/ show the same information. I’m using the WordPress SEO plugin to output the canonical URL in the header, and it shows my pretty permalink.

In menus on the site, linking to the category shows the pretty URL.

My question is, why doesn’t the URL of “/?cat=22” get automatically redirected to it’s pretty permalink like every other link on the site?

I made another parent category which didn’t have this issue. Is news a stopword or keyword? How do I go about trouble-shooting this? I am trying to avoid editing the .htaccess file with a custom rule for this one issue, as I’d rather get to the root of the problem.

The site is behind a firewall at present so it is not publicly visible. Thanks for any and all help / light shed on this subject.