Recently selecting both/either ‘Aggregate and compress CSS files’ and ‘Aggregate JavaScript files’ in the Performance window seems to have stopped working on a D7 site. When they are selected the CSS/JS will not load.
I have cloned the site on another dev server, and the problem does not occur there. The server PHP versions are the same. The Drupal version is the latest at the time of writing: 7.89.
How can I debug what is going on here?