Cannnot turn off aggregation. Could it be due to server settings?

I am working on a site and two days ago I saw some of the styles on the site disappear. I check the Performance settings in Configuration, CSS and JS aggregation were off. I asked the server maintenance person if they somehow turned this feature on and they said no.

When I actually turn on aggregation in Drupal, the sites looks normal. But I can’t continue working on the front end like this and I can’t get rid of aggregation no matter what. The /sites/default/files/css and js directories are full of gzipped CSS and JS files and the page source points to files such as /sites/all/themes/mytheme/css/A.styles,,qnidx…(etc).

I also checked the settings.php file, the only suspicious thing is the $drupal_hash_salt variable which is uncommented and has a value. It was not me who set this up.

My presumption is that the server maintenance person turned on some security features which also affect the loading of the CSS files.

Edit: I am using the Zen theme, but even when I change it to Bartik, I get the same problem

Any ideas?