It's expected behavior (even if it's not really clear or friendly). The actual menu item is for the category blog, and you've created 3 menu items for the same category. The tags selection is designed to create an additional filter for that view, but on its own doesn't affect routing.

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/17052

closed as expected Behaviour. It can always reopened for further Discussion.

@mahagr Even if all three are (Category, Blog), then the path of the article is all (windows/articleid-1.html);

Whether I can be so understanding, namely the first menu must be no label the menu list; if not, then the logic is wrong, because I cannot make use of (Linux) (Windows) of the menu path.

@mbabker My translation may not be accurate, should not be used (routing), and use (path) a bit more accurate.

It is a routing issue. When you have multiple menu items configured to show the same content (in this case, your OS category using the category blog view), when links are generated the system uses the first menu item that matches the configuration. So in your case, Joomla generates all of the URLs as /os/1-article.html but you can manually input /windows/1-article.html and /linux/1-article.html to get to the same content since you have menu items configured with each of those paths.