Hi Andy!
It should work as you have described!
To clarify. The logic of the module is to have a category ID parameter in the URL. Module filters by the concrete category. It can work on the single article page. The code is quite simple:
$catid = $params->get('catid', 1);
if ($option === 'com_content' && $view === 'category') {
$catid = $input->getInt('id');
} elseif ($option === 'com_content' && $view === 'article') {
$catid = $input->getInt('catid', $catid);
}
The module gets the default category from the module settings.
If view=category (blog) then it takes id from URL.
If view=article (single page) then it takes catid from URL, but if not found, then it gets the default category from the module settings.
I an not sure why it does not work in your case - shows all the articles in category 'събития' (events) instead of just the articles with that date. Is seems that filtering does not work.
Is "System - Calendar Filter" plugin published? It is responsible for filtering.
If it is published, it would be good if you can provide FTP access to your dev site for debugging. Just update the Credentials section (it is not visible for public).
Kind regards,
Dmitrijs