Make sure you are not blocking content.

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?

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

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}

Thanks @FredMcD.

As part of my effort to diagnose the problem, I did clear the cache, search history, form data, and download history. Then I ran Firefox in safe mode, and found that AA.com worked fine. Next step, I put Firefox in normal operating mode but disabled all my extensions and plug-ins. I started by re-enabling Lastpass so I had access to passwords, then one by one re-enabled other extensions. It seems that Google Analytics Opt-out Add-on (by Google) may have been the culprit because, when I put an exception for AA.com into that add-on, AA.com loaded. Re-enabling the rest of my add-ins and extensions caused no other issues.

I'm not enirely happy with that solution as I don't like to give Google any more information about me than they already have. I'll take a look at Firefox's SmartBlock for Enhanced Tracking Protection feature to see if that will solve the problem that I was trying to do with the Google add-in. It's been awhile since I read up on SmartBlock for Enhanced Tracking Protection.

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.

You should contact the add-ons support for more help on this.

All, I was able to fix my problem in a different way by reading this thread (thank you!). I started looking at all the problems with Plug-ins. For me, the problem was a "Duck Duck Go" privacy plug in/add on. I didn't disable the plug in entirely, just for the aa.com site itself. That fixed my issue. Not sure why aa.com doesn't like that. Problem solved though.

All, I was able to fix my problem in a different way by reading this thread (thank you!). I started looking at all the problems with Plug-ins. For me, the problem was a "Duck Duck Go" privacy plug in/add on. I didn't disable the plug in entirely, just for the aa.com site itself. That fixed my issue. Not sure why aa.com doesn't like that. Problem solved though.

Thanks for your contribution here. Good to keep the Duck Duck Go Privacy Essentials plug-in in mind when troubleshooting other issues in the future.