If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock,NoScript,DuckDuckGo PE,Disconnect,Ghostery,uBlock Origin,Malwarebytes), always make sure such extensions do not block content. *make sure your extensions and filters are updated to the latest version *https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems You can check for issues with Enhanced Tracking Protection and Total Cookie Protection. Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content. *click the shield icon for more detail and possibly disable the protection You can check the Web Console for relevant-looking messages like about blocked content. *https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop *https://support.mozilla.org/en-US/kb/total-cookie-protection-and-website-breakage-faq *https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

I turned off Hardware acceleration. That solved the problem.