At production I had added FAQ based on https://www.youtube.com/watch?v=GTw3rzcPC9k . On staging it worked fine but now on production the newly added FAQstyle CSS added under manage > stylesheets was not loading.

So I did the following

• Emptied WP Rocket cache though I should not need to as I am a logged in user,
• Regenerated Oxygen CSS cache
• Loaded the page with cache checked as turned off (Firefox Inspector) and
• loaded page in private window and another browser
• Emptied Redis Object Caching

Now joy, still answers are loaded right away and style:

div.panel {
 max-height: 0; 
overflow: hidden; opacity: 0;}
div.panel.show {
 opacity: 1; 
min-height: 200px;
}

was not loaded.

Issue and Solution

So what was going on here? I asked Oxygen Support for their feedback. Soph there found out the home style sheet had a quote missing on an image url and a closing brace was missing elsewhere. This caused the next style sheet not to be included in the universal.css.