WordPress page not showing up – replaced with last 10 posts?

The problem is with the rewrite rules generated with the post type- they’re a bit greedy and are capturing those requests. WordPress is trying to query for a matching category_type, which isn’t actually an object type, and in the absence of any other valid query argument, it runs the main blog query.

You could manually generate the post type rewrite rules in a way that is less greedy, or you can add a rule that just overrides them in the case where ARTICLE_NAME isn’t present:

add_rewrite_rule(
    '^community/articles/([^/]*)?/?$',
    'index.php?pagename=community/articles/$matches[1]',
    'top'
);

When dealing with rewrites, I recommend the Monkeyman Rewrite Analyzer plugin, which will give you a new menu item in admin under Tools where you can plug in URLs and see how they are matching to rewrite rules and parsing to query vars.