I tried following steps you suggested, but still, header builder is not working, I am willing to provide my admin panel login details of my website, may I know where I can send the credentials by mail or in this reply area itself, but make sure that it won’t be in the public
I have deactivated all the third party plugins and Regenerated the CSS file and the Header builder is working absolutely fine on my end. Please disable server caching, clear browser cache and check back.