Make sure you are not blocking content.

https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/

https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection

Diagnose Firefox issues using Troubleshoot(Safe) Mode {web link}

A small dialog should appear. Click Start In Troubleshoot(Safe) Mode (not Refresh). Is the problem still there?

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Delete cookies to remove the information websites have stored on your computer {web link}

• How to clear the Firefox cache {web link}

I had the same problem a few weeks. Solved by deleting all Vanguard cookies. Settings, Privacy & Security, Cookies and Site Data Click on Manage Data, search for vanguard and delete any cookies found Close & restart FF

Thanks to all for your suggestions. Unfortunately none had any effect. I finally decided to look at the Login Passwords I had saved and erased all of them. I then re-entered my login information and it all worked.

That was very good work. Well Done. Please flag your last post as Solved Problem as this can help others with similar problems. Go to that post and click the 'Solved' button to its right.

Manually entering my login info instead of using autofill fixed the problem for me.