Privacy Possum is blocking a lot when you get to the sign in page. Try disabling it and refresh the page.

There is also DuckDuckGo Privacy Essentials showing in the System Details list as an extension that can block content. If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) 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 Firefox shows an highlighted shield icon at the left end of the location/address bar in case Tracking Protection is blocking content. *click the shield icon for more details and possibly disable the protection You can check in the Web Console what content is blocked *"3-bar" menu button or Tools -> Web Developer *https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop You can check in the Web Console if there is more detail available when you have a problem with logging in. *"3-bar" menu button or Tools -> Web Developer