Missing icons are usually supplied by a font that is downloaded from the server (@font-face) as you might see by little boxes that show the hex code of the characters instead. If you have a font installed that covers this Unicode range then you may see a real (CJK) character and not the little box with the CSS code.

Make sure that you allow pages to choose their own fonts.

• Tools > Options > Content : Fonts & Colors > Advanced: [X] "Allow pages to choose their own fonts, instead of my selections above"

You can check the gfx.downloadable_fonts.enabled pref on the about:config page and make sure that it is set to true (if necessary double-click the line to toggle its value).

Thank you for your post. Yes, as I mentioned in my original post I have already confirmed this setting in the GUI and in the about:config settings. After doing that I disabled all extensions, restarted FF, and confirmed the issue persists. No firewall or AV software on this machine.

Did you check the gfx.downloadable_fonts.enabled on the about:config page?

It is possible that you have security software that is blocking the files.

If you have Avast then try to disable HTTPS scanning in Avast Web Shield.

• http://www.ghacks.net/2014/10/31/avasts-https-scanning-interferes-with-firefox-and-other-programs/
• https://forum.avast.com/index.php?topic=176073.0

Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) to see if that has effect.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

Did you check the gfx.downloadable_fonts.enabled on the about:config page?

Yes

I have not AV software or firewall software installed. Going to install Win10 in a VM and see if I can replicate. Other browsers (IE, Chrome) are unaffected.

See also these threads:

• [/questions/1080251] web page not showing icons
• [/questions/1079809] Firefox 40 failing to display all buttons (only shows framework for buttons) on MSN and Yahoo email sites

You can check the Net log and the Network log in the Web Console (Firefox/Tools > Web Developer) to see if content fails to load or possibly is blocked (file size is zero).

• https://developer.mozilla.org/Tools/Network_Monitor

Use Ctrl+F5 or Ctrl+Shift+R to reload the page and bypass the cache to generate a fresh log.

I used the network view in the web developer console to confirm the fonts are downloading. I can verify there are no download errors at all (all green for the Get method) and can see .ttf and .woff octet-stream file types downloading normally. Seems to be an issue with the rendering. Will reference the other threads and try the safe mode stuff and let you know.

I started FF in safe mode and still having the issue. Going to test in a Win10 VM and see if I can replicate. So far here is what I know, Win 7 = no problem. Upgrade 7 to Win 10 = problem only affecting FF.

I did some more testing and found that IE was not displaying anything where the icons (fancy fonts) should be. Chrome displayed them perfectly fine. So, IE nothing, and Firefox with the boxes with hex code.

I just rebuilt my machine and now everything is working. That was fun. Clean install of Windows 7, upgrade to Windows 10, re-install Firefox, and now working. Suspect some kind of font corruption with the upgrade from 7 to 10.

I found the root cause of the issue. In Windows 10 when the WIndows Firewall service is stopped (I like it disabled as I run a perimeter FW) the issue occurs. Start the Windows Firewall service and everything is fine. Hope this helps others.