Website Pop opens up blank unless inspected

Question

Website: https://new.arabschools.edu.sa Button: Menu (Top right)

The menu pop opens up blank unless inspected via the browser webtool.

Caching is disabled. I'm at my wits end. Multiple browsers.

The menu pop up should open and display normally until recently. I've disabled all plugins as well.

Answer 1

I've found that refreshing/reloading the page solves the issue.

Root Cause: The CSS style not applied until refresh

Unsure on how to resolve this on Wordpress